[M] Change in flashrom[master]: tests: Detect llvm coverage file io and unmock io functions

[Anastasia Klimchuk (Code Review)]

Attention is currently required from: Evan Benn.

Anastasia Klimchuk has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/69267 )

Change subject: tests: Detect llvm coverage file io and unmock io functions
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Patch Set 10:

(4 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/69267/comment/f3e08fd3_587611ed 
PS10, Line 7: tests: Detect llvm coverage file io and unmock io functions
Could you please re-use my comments for commit message from the previous patch into here, too? thanks!

File Documentation/building.md:

https://review.coreboot.org/c/flashrom/+/69267/comment/2097605a_aee8f9b5 
PS10, Line 52: 
             : #### gcc / gcov
This line needs to be in a previous patch, where the section is added

File tests/unmock_io.c:

https://review.coreboot.org/c/flashrom/+/69267/comment/a4bc875d_4582a185 
PS10, Line 32: (void)state;
can be dropped

https://review.coreboot.org/c/flashrom/+/69267/comment/e75d9d4c_14adf93e 
PS10, Line 79: ".gcda"
Can this go into macro at the beginning of the file?
GCOV_COVERAGE_FILE
LLVM_COVERAGE_FILE