[HAVE_GTK_AND_PTHREAD] Check this after including config.h.

[HAVE_GTK_AND_PTHREAD] Check this after including config.h.
(_aligned_blocks_mutex) [USE_PTHREAD]: New variable.
(LOCK_ALIGNED_BLOCKS, UNLOCK_ALIGNED_BLOCKS): New macros.
(_free_internal, memalign): Use them.
(_malloc_mutex, _aligned_blocks_mutex) [USE_PTHREAD]:
Initialize to PTHREAD_MUTEX_INITIALIZER.
(malloc_initialize_1) [USE_PTHREAD]: Don't use recursive mutex.
(morecore_nolock): Rename from morecore.  All uses changed.
Use only nolock versions of internal allocation functions.
(_malloc_internal_nolock, _realloc_internal_nolock)
(_free_internal_nolock): New functions created from
_malloc_internal, _realloc_internal, and _free_internal.
(_malloc_internal, _realloc_internal, _free_internal): Use them.
Copy hook value to automatic variable before its use.
(memalign): Copy hook value to automatic variable before its use.