[Sanitizers] Fix SanitizerCommon-Unit ::...

[Sanitizers] Fix SanitizerCommon-Unit :: ./Sanitizer-*-Test/MemoryMappingLayout.DumpListOfModules on Solaris

The MemoryMappingLayout.DumpListOfModules currently FAILs on Solaris:

  [ RUN      ] MemoryMappingLayout.DumpListOfModules
  /vol/llvm/src/compiler-rt/local/lib/sanitizer_common/tests/sanitizer_procmaps_test.cc:52: Failure
  Value of: found
    Actual: false
  Expected: true
  [  FAILED  ] MemoryMappingLayout.DumpListOfModules (22 ms)

The problem is that the test expects the executable name from modules[i].full_name(),
however the pr_mapname field of struct prmap is just the entry in /proc/<pid>/object,
which is "a.out" instead of "Sanitizer-i386-Test".  Fortunately, the real name can
be determined by looking in proc/<pid>/path where "a.out" is a symlink to the
real path.

Tested on x86_64-pc-solaris2.11.

Differential Revision: https://reviews.llvm.org/D64559

llvm-svn: 365879