Resubmissions of https://github.com/llvm/llvm-project/pull/112596 with
buildbot fixes.

Allow LLDB to parse the dynamic symbol table from an ELF file or memory
image in an ELF file that has no section headers. This patch uses the
ability to parse the PT_DYNAMIC segment and find the DT_SYMTAB,
DT_SYMENT, DT_HASH or DT_GNU_HASH to find and parse the dynamic symbol
table if the section headers are not present. It also adds a helper
function to read data from a .dynamic key/value pair entry correctly
from the file or from memory.

This reverts commit a7b2e73bcaa91255a20f1f2e692bec9eb6c17022.

This patch broke the greendragon bot

Failed Tests (10):
  lldb-api :: python_api/sbplatform/TestLocateModuleCallback.py
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleCallbackSuccessWithModuleAndSymbol
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleCallbackSuccessWithOnlySymbol
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleCallbackSuccessWithSymbolAsModule
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleCallbackSuccessWithSymbolAsModuleAndSymbol
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleCallbackSuccessWithSymbolByPlatformUUID
  lldb-unit :: Target/./TargetTests/LocateModuleCallbackTest/GetOrCreateModuleWithCachedModuleAndSymbol
  lldb-unit :: Target/./TargetTests/ModuleCacheTest/GetAndPut
  lldb-unit :: Target/./TargetTests/ModuleCacheTest/GetAndPutStrangeHostname
  lldb-unit :: Target/./TargetTests/ModuleCacheTest/GetAndPutUuidExists

Allow LLDB to parse the dynamic symbol table from an ELF file or memory
image in an ELF file that has no section headers. This patch uses the
ability to parse the PT_DYNAMIC segment and find the DT_SYMTAB,
DT_SYMENT, DT_HASH or DT_GNU_HASH to find and parse the dynamic symbol
table if the section headers are not present. It also adds a helper
function to read data from a .dynamic key/value pair entry correctly
from the file or from memory.

This patch improves the ability of a ObjectFileELF instance to read the
.dynamic section. It adds the ability to read the .dynamic section from
the PT_DYNAMIC program header which is useful for ELF files that have no
section headers and for ELF files that are read from memory. It cleans
up the usage of the .dynamic entries so that
ObjectFileELF::ParseDynamicSymbols() is the only code that parses
.dynamic entries, teaches that function the read and store the string
values for each .dynamic entry. We now dump the .dynamic entries in the
output of "image dump objfile". It also cleans up the code that gets the
dynamic string table so that it can grab it from the DT_STRTAB and
DT_STRSZ .dynamic entries for when we have a ELF file with no section
headers or we are reading it from memory.

This reverts commit 28ba8a56b6fb9ec61897fa84369f46e43be94c03.

Reverting since this broke the buildbot at
https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/as-lldb-cmake/9352/.

This patch improves the ability of a ObjectFileELF instance to read the .dynamic section. It adds the ability to read the .dynamic section from the PT_DYNAMIC program header which is useful for ELF files that have no section headers and for ELF files that are read from memory. It cleans up the usage of the .dynamic entries so that ObjectFileELF::ParseDynamicSymbols() is the only code that parses .dynamic entries, teaches that function the read and store the string values for each .dynamic entry. We now dump the .dynamic entries in the output of "image dump objfile". It also cleans up the code that gets the dynamic string table so that it can grab it from the DT_STRTAB and DT_STRSZ .dynamic entries for when we have a ELF file with no section headers or we are reading it from memory. 

It was pointed out that ordering is crucial here, so note that.

I also looked into using a vector instead, as described in
https://llvm.org/docs/ProgrammersManual.html#dss-sortedvectorset.

Which this is in theory perfect for, but we have at least 2 places
that update the map and both would need to sort/unique each time.
Plus this code is pretty bug prone.

If there is future refactoring it's one thing to consider.

Instead of updating the member of the ObjectFileELF instance. This means
that if one object file asks another to parse the symbol table, that
first object's can update its address class map with the same changes
that the other object did.

(I'm not returning a reference to the other object's m_address_class_map
member because there may be other things in there not related to the
symbol table being parsed)

This will fix the code added in
https://github.com/llvm/llvm-project/pull/90622 which broke the test
`Expr/TestStringLiteralExpr.test` on 32 bit Arm Linux.

This happened because we had the program file, then asked for a better
object file, which returned the same program file again. This creates a
second ObjectFileELF for the same file, so when we tell the second
instance to parse the symbol table it actually calls into the first
instance, leaving the address class map of the second instance empty.

Which caused us to put an Arm breakpoint instuction at a Thumb return
address and broke the ability to call mmap.

This patch replaces (llvm::|)Optional< with std::optional<.  I'll post
a separate patch to clean up the "using" declarations, #include
"llvm/ADT/Optional.h", etc.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716