Since 2916b99182752b1aece8cc4479d8d6a20b5e02da this is just an alias to
std::optional, and by now it has been removed entirely.

Remove the testing for std::optional - it was originally for
llvm::Optional, but now that that doesn't exist and we use
std::optional, testing for that pretty printer should live, wherever the
pretty printer lives, not here in LLVM.

And the PointerIntPair pretty printer bit rotted due to changes in
PointerIntPair, 875391728c11339c8a6cd3338bcaa5ec0ffc2496.

This is the first commit in a series that will reformat
all the python files in the LLVM repository.

Reformatting is done with `black`.

See more information here:

https://discourse.llvm.org/t/rfc-document-and-standardize-python-code-style

Reviewed By: jhenderson, JDevlieghere, MatzeB

Differential Revision: https://reviews.llvm.org/D150545

Some GDB versions require all prettyprinter classes to define to_string.
This commit adds these definitions.

Reviewed By: csigg

Differential Revision: https://reviews.llvm.org/D127969

This isn't perfect, since it doesn't use lazy_string - so if the
std::string does contain unprintable characters it might fail, but seems
better than nothing & LLVM doesn't generally store binary data in
std::strings.

Still some pending bugs, but at least ironed some things out.

Instead of using the type llvm::StringMapEntry<{stringified_value_type}>
use only the base class llvm::StringMapEntryBase and calculate the
offsets of the member variables manually. The approach with stringifying
the name of the value type is pretty fragile as it can easily break with
local and dependent types.

Differential Revision: https://reviews.llvm.org/D94431