Refactor: Renamed internal stack dump function
Refactor: Renamed internal stack dump function

Some compilers generate a warning for symbols starting with double
underscores causing a build break. Renamed the function to
libmemcached_stack_dump instead, and added an implementation for
Solaris while I'm touching the code

trondn/libmemcached,trondn/libmemcached,trondn/libmemcached,trondn/libmemcached,trondn/libmemcached