(bfd_zmalloc): Return PTR, not char *. Take size_t, not
bfd_size_type.
* libbfd-in.h (bfd_malloc, bfd_realloc): Declare.
(bfd_zmalloc): Change declaration.
* libbfd.h: Rebuild.
* Many files: Use bfd_malloc and bfd_realloc rather than malloc
and realloc. Don't set bfd_error_no_memory if they fail.
obstack_alloc fails.
(bfd_alloc_finish): Set bfd_error_no_memory if obstack_finish
fails.
* libbfd.c (bfd_zmalloc): Set bfd_error_no_memory if malloc fails.
* Many files: don't set bfd_error_no_memory if one of the above
routines fails.
