* string.h: Re-enable inline strcasematch and strncasematch

implementations and rename to ascii_strcasematch/ascii_strncasematch.
	* dcrt0.cc: Replace str[n]casematch with ascii_str[n]casematch where
	applicable.
	* environ.cc: Ditto.
	* fhandler_process.cc: Ditto.
	* hookapi.cc: Ditto.
	* path.cc: Ditto.
	* spawn.cc: Ditto.
	* strace.cc: Ditto.
	* syscalls.cc: Ditto.
	* uinfo.cc: Ditto.
	* winf.cc: Ditto.

winsup/cygwin/winf.cc

@@ -141,7 +141,7 @@ av::unshift (const char *what, int conv)
     {
       cygwin_conv_to_posix_path (what, buf);
       char *p = strchr (buf, '\0') - 4;
-      if (p > buf && strcasematch (p, ".exe"))
+      if (p > buf && ascii_strcasematch (p, ".exe"))
 	*p = '\0';
       what = buf;
     }