[sanitizer_common] Rewrite more Posix tests to use asserts

Rewrite the tests for Posix functions that silently 'return 1'
or 'exit(1)' on error, to instead verbosely report the error using
assert.  This is based on requests made in review of D56136.

Differential Revision: https://reviews.llvm.org/D56149

llvm-svn: 350227