[compiler-rt] [llvm-cov] Test for "Don't remap existing paths"

[greened]

Summary

This is a test for the llvm-cov change to not remap paths for source files that exist. It lives in compiler-rt because it uses clang to generate the profiled binary. It doesn't seem possible to create a static binary for a test within llvm because such a static binary will necessarily encode a fixed source path which may not even exist in the developers workarea. A test using clang to generate the binary makes it "relocatable" to whatever build setup the developer has.

[greened]

Corresponding differential is here:

https://reviews.llvm.org/D53729

test/profile/coverage-path-test.cpp

+// REQUIRES: shell
+// RUN: mkdir -p %t/a/b
+// RUN: cp %s %t/a/b/coverage-path-test.cpp
+// RUN: %clang_profgen -fuse-ld=gold -O2 -fdata-sections -ffunction-sections -fcoverage-mapping -Wl,--gc-sections -o %t/a/b/coverage-path-test.exe %t/a/b/coverage-path-test.cpp
+// RUN: env LLVM_PROFILE_FILE=%t/a/b/coverage-path-test.exe.profraw %run %t/a/b/coverage-path-test.exe
+// RUN: llvm-profdata merge -o %t/a/b/coverage-path-test.exe.profdata %t/a/b/coverage-path-test.exe.profraw
+// RUN: llvm-cov show %t/a/b/coverage-path-test.exe -instr-profile %t/a/b/coverage-path-test.exe.profdata -path-equivalence=%t/a,%t/a/b 2>&1 | FileCheck %s
+
+// CHECK: [[@LINE+1]]| 1|int main
+int main(int argc, const char *argv[]) {}