use assembly code matcher when possible

use assembly code matcher when possible

* configure.ac (ASCPPPOST): Backslash-escape "#" in AC_SUBST'd
variable, to keep make from seeing it as a comment-introducer.
Based on a patch by Petr Pisar.
* lib/Makefile.am (match.$(OBJEXT)): Use AM_V_GEN and AM_V_at.
* lib/match.c: Don't include <config.h>.
It would impede configure-time assembler test.
* .x-sc_require_config_h: Exempt lib/match.c from syntax-check.
* .x-sc_require_config_h_first: Likewise.