This corrects the debug information for the cloned functions so that it
contains the correct linkage name.

During the whole program reporting of contexts when hinted byte
reporting is enabled via -memprof-report-hinted-sizes, also print the
internal context id. This is useful for debugging, as well as for
guiding the dot file dumping with some upcoming changes that will
accept a context id to focus the graph on a context of interest.

Two misc cleanup/improvements to the dot printing.

Remove a redundant "style=filled" in the Node attributes. No effect on
resulting graph.

Add a "color" attribute to the Edge, with the same color name as
"fillcolor". The latter only fills in the arrowhead, and the former is
what affects the line. This makes the edge colors more visible,
previously it was a black edge with a colored in arrowhead.

For the second change, I added the new Edge color attributes to the
checking in the two "basic.ll" tests, so we get some testing coverage of
the full printing. For the other affected tests I removed the final "]'"
after the fillcolor so it matches up through that attribute and ignores
the rest of the line.

Improve the information printed when -memprof-report-hinted-sizes is
enabled. Now print the full context hash computed from the original
profile, similar to what we do when reporting matching statistics. This
will make it easier to correlate with the profile.

Note that the full context hash must be computed at profile match time
and saved in the metadata and summary, because we may trim the context
during matching when it isn't needed for distinguishing hotness.
Similarly, due to the context trimming, we may have more than one full
context id and total size pair per MIB in the metadata and summary,
which now get a list of these pairs.

Remove the old aggregate size from the metadata and summary support.
One other change from the prior support is that we no longer write the
size information into the combined index for the LTO backends, which
don't use this information, which reduces unnecessary bloat in
distributed index files.

If requested, via the -memprof-report-hinted-sizes option, track the
total profiled size of each MIB through the thin link, then report on
the corresponding allocation coldness after all cloning is complete.

To save size, a different bitcode record type is used for the allocation
info when the option is specified, and the sizes are kept separate from
the MIBs in the index.

Adds an LTO option to indicate that whether we are linking with an
allocator that supports hot/cold operator new interfaces. If not,
at the start of the LTO backends any existing memprof hot/cold
attributes are removed from the IR, and we also remove memprof metadata
so that post-LTO inlining doesn't add any new attributes.

This is done via setting a new flag in the module summary index. It is
important to communicate via the index to the LTO backends so that
distributed ThinLTO handles this correctly, as they are invoked by
separate clang processes and the combined index is how we communicate
information from the LTO link. Specifically, for distributed ThinLTO the
LTO related processes look like:
```
   # Thin link:
   $ lld --thinlto-index-only obj1.o ... objN.o -llib ...
   # ThinLTO backends:
   $ clang -x ir obj1.o -fthinlto-index=obj1.o.thinlto.bc -c -O2
   ...
   $ clang -x ir objN.o -fthinlto-index=objN.o.thinlto.bc -c -O2
```

It is during the thin link (lld --thinlto-index-only) that we have
visibility into linker dependences and want to be able to pass the new
option via -Wl,-supports-hot-cold-new. This will be recorded in the
summary indexes created for the distributed backend processes
(*.thinlto.bc) and queried from there, so that we don't need to know
during those individual clang backends what allocation library was
linked. Since in-process ThinLTO and regular LTO also use a combined
index, for consistency we query the flag out of the index in all LTO
backends.

Additionally, when the LTO option is disabled, exit early from the
MemProfContextDisambiguation handling performed during LTO, as this is
unnecessary.

Depends on D149117 and D149192.

Differential Revision: https://reviews.llvm.org/D149215

This reverts commit f09807ca9dda2f588298d8733e89a81105c88120, restoring
bfe7205975a63a605ff3faacd97fe4c1bf4c19b3 and follow on fix
e3e6bc699574550f2ed1de07f4e5bcdddaa65557, now that the nondeterminism
has been addressed by D149924.

Differential Revision: https://reviews.llvm.org/D141077

This reverts commit bfe7205975a63a605ff3faacd97fe4c1bf4c19b3, and follow
on fix e3e6bc699574550f2ed1de07f4e5bcdddaa65557, due to some remaining
instability exposed by the bot enabling expensive checks:
https://lab.llvm.org/buildbot/#/builders/42/builds/9842

Follow up to bfe7205975a63a605ff3faacd97fe4c1bf4c19b3 to require asserts
which is needed for the use of -stats. This showed up in the following
bot failure: https://lab.llvm.org/buildbot/#/builders/91/builds/16760

This reverts commit 6fbf022908c104a380fd1854fb96eafc64509366, restoring
commit bf6ff4fd4b735afffc65f92a4a79f6610e7174c3 with a fix for a bot
failure due to a previously unstable iteration order.

Differential Revision: https://reviews.llvm.org/D141077