[TSan] Add AnnotateIgnoreReadsBegin declaration to tsan/test.h

Declare the family of AnnotateIgnore[Read,Write][Begin,End] TSan
annotations in compiler-rt/test/tsan/test.h so that we don't have to
declare them separately in every test that needs them.  Replace usages.

Leave usages that explicitly test the annotation mechanism:
  thread_end_with_ignore.cpp
  thread_end_with_ignore3.cpp

llvm-svn: 371446