[asan] Correctly release memory allocated during early startup.

Calloc interceptor initially allocates memory from temp buffer (to serve dlsyms called during asan_init). There is a chance that some non-instrumented library (or executable) has allocated memory with calloc before asan_init and got pointer from the same temporary buffer which later caused problems with free.

Inspired by https://github.com/google/sanitizers/issues/626

Differential Revision: http://reviews.llvm.org/D14979

llvm-svn: 254395