Details:
- Fixed a sort-of bug in bli_init.c whereby the wrong pthread mutex
was used to lock access to initialization/finalization actions.
But everything worked out okay as long as bli_init() was called by
single-threaded code.
- Changed to static initialization for memory allocator mutex in
bli_mem.c, and moved mutex to that file (from bli_init.c).
- Fixed some type mismatches in bli_threading_pthreads.c that resulted
in compiler warnings.
- Fixed a small memory leak with allocated-but-never-freed (and unused)
pthread_attr_t objects.
- Whitespace changes to bli_init.c and bli_mem.c.
1213f5ceba