Cleanup utilities. Introduce sxe-memory.h
Move all the memory related utilities to sxe-memory.h so that
sxe-utils.h can be included in contexts where the memory utils
are not welcome.
* src/sxemacs.h: Remove include for sxe-utils.h, lisp.h already
does it.
* src/lisp.h: Include new sxe-memory.h
* src/sxe-utils.h: Remove xnew, xnew_atomic, xnew_array,
xnew_atomic_array, xnew_and_zero, xzero, xnew_array_and_zero,
xrealloc_array, alloca_array, xstrdup
* src/sxe-memory.h: Add definitions removed from sxe-utils.
Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>