const char* tc_version(int* major, int* minor, const char** patch);

The variable is the same: 'version_malloc_library'
The output for tcmalloc currently looks like: tcmalloc gperftools 2.4

1. guess_malloc_library.cc looks like pure C and a generally useful helper, so it'd make sense to move it to mysys/guess_malloc_library.c (and in this case guess_malloc_library.h is not needed, the prototype can be in my_sys.h.
2. declare only one static char [128] buffer, not two.
3. #ifndef HAVE_DLOPEN is good, but put the rest of the function in the #else branch (so that compiler wouldn't see dlsym()).

otherwise looks good, thanks!

Just one more change and ok to push into bb-10.2-ext:

• move static char buf[128]; declaration to be before the very first statement, as C90 requires. We still get compiled with old compilers from time to time.

Roger that