[Sanitizer] Don't die in symbolizer if it can't read /proc/self/exe link

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@179754 91177308-0d34-0410-b5e6-96231b3b80d8
[Sanitizer] Rework r176802: share code between Printf and Report and simplify it a bit

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@179755 91177308-0d34-0410-b5e6-96231b3b80d8