fix: sccache does not generate new object file if "-gsplit-dwarf" is enabled and the filename or directory of the object is changed

[zhouronghua]

when output dir changed, and -g -gsplit-dwarf is enabled, new object file should be gererated, but not old cached object.

case:

1 echo "int test(){}" > test.cc

2 mkdir o1 o2

3 sccache g++ -c -g -gsplit-dwarf test.cc -o o1/test.o

4 sccache -z

5 sccache g++ -c -g -gsplit-dwarf test.cc -o o2/test.o

6 strings o2/test.o |grep o2/test.dwo

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 40.60%. Comparing base (0cc0c62) to head (0e3db1b). Report is 78 commits behind head on main.

Files with missing lines	Patch %	Lines
src/compiler/gcc.rs	16.66%	0 Missing and 5 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2264 +/- ## ========================================== + Coverage 30.91% 40.60% +9.69% ========================================== Files 53 54 +1 Lines 20112 20713 +601 Branches 9755 9630 -125 ========================================== + Hits 6217 8410 +2193 - Misses 7922 8142 +220 + Partials 5973 4161 -1812 ```

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[sylvestre]

the patch doesn't apply and what is "INF-2296" ? :)

[sylvestre]

the patch has nothing to do with split dwarf. please reopen when it is fixed

[zhouronghua]

sorry for I have not replied in holiday.

I didn't find way to reopen the PULL REQUEST, so I create another PR in https://github.com/mozilla/sccache/pull/2264