tsan: Optimize performance of Thread sanitizer memory access functions

- Manually unwind code in MemoryAccessImpl1() because clang do not optimize it
- Check for .rodata section only in read operations
- Place LIKELY/UNLIKELY on fast paths

This speeds up synthetic memory access benchmarks by 10-20%.

[dvyukov: fixed up consts in check_analyze.sh]

Author: yuri (Yuri Per)
Reviewed in: https://reviews.llvm.org/D57882
Context: https://reviews.llvm.org/D54889

llvm-svn: 353401