objtool/klp: klp-build LTO support

Add support for LTO in klp-build toolchain. The key changes are to the symbol correlation logic.Basically, we want to:

1. Match symbols with differerent .llvm.<hash> suffixes, e.g., foo.llvm.123 to foo.llvm.456.
2. Match local symbols with promoted global symbols, e.g., local foo with global foo.llvm.123.

1/7 and 2/7 are small cleanup/fix for existing code.
3/7 through 7/7 contains the core logic changes to correlate_symbols().

Changes v3 => v4:
1. Minor fixes in patches 1, 3, 7.
2. Only keep patches 1-7 for now, as there is ongoing discussion about the test infrastructure.

Changes v2 => v3:
1. Fix a bug in global => local correlations (patch 7/8).
2. Remove a WARN().
3. Some empty line changes.

Changes v1 => v2:
1. Error out on ambiguous .llvm.<hash>

Song Liu (7):
objtool/klp: Remove redundant strcmp() in correlate_symbols() objtool/klp: Remove trailing '_' in demangle_name() objtool/klp: Use sym->demangled_name for symbol_name hash objtool/klp: Also demangle global objects objtool/klp: Remove .llvm suffix in demangle_name() objtool/klp: Match symbols based on demangled_name for global
variables
objtool/klp: Correlate locals to globals

 tools/objtool/elf.c                 | 95 ++++++++++++++++++++++-------
 tools/objtool/include/objtool/elf.h |  3 +
 tools/objtool/klp-diff.c            | 89 ++++++++++++++++++++++++++-
 3 files changed, 165 insertions(+), 22 deletions(-)

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2.52.0