Moved cpp macro redef of strerror_r to bli_env.c.

Details:
- Relocated the _MSC_VER-guarded cpp macro re-definition of strerror_r
  (in terms of strerror_s) from bli_thread.h to bli_env.c. It was
  likely left behind in bli_thread.h in a previous commit, when code
  that now resides in bli_env.c was moved from bli_thread.c. (I couldn't
  find any other instance of strerror_r being used in BLIS, so I moved
  the #define directly to bli_env.c rather than place it in bli_env.h.)
  The code that uses strerror_r is currently disabled, though, so this
  commit should have no affect on BLIS.

frame/thread/bli_thread.h

@@ -61,10 +61,6 @@
 void bli_thread_init( void );
 void bli_thread_finalize( void );
 
-#ifdef _MSC_VER
-#define strerror_r(errno,buf,len) strerror_s(buf,len,errno)
-#endif
-
 // Thread range-related prototypes.
 
 BLIS_EXPORT_BLIS