_dl_exception_create_format: Support %x/%lx/%zx

Add support for %x, %lx and %zx to _dl_exception_create_format and pad
to the full width with 0.

	* elf/Makefile (tests-internal): Add tst-create_format1.
	* elf/dl-exception.c (_dl_exception_create_format): Support
	%x, %lx and %zx.
	* elf/tst-create_format1.c: New file.