Retire GNU_GREP_COMPAT knob

This was introduced and then disabled by default primarily to avoid dealing
with bugs in libgnuregex. rS363823 switched to using libregex for it, so
let's just rip the option out now so we can make sure we're getting tested
with libregex via bsdgrep.

Reviewed by:	emaste
Differential Revision:	https://reviews.freebsd.org/D27476

share/mk/src.opts.mk

@@ -208,7 +208,6 @@ __DEFAULT_NO_OPTIONS = \
     CLANG_FORMAT \
     DTRACE_TESTS \
     EXPERIMENTAL \
-    GNU_GREP_COMPAT \
     HESIOD \
     LIBSOFT \
     LOADER_FIREWIRE \

tools/build/options/WITHOUT_GNU_GREP_COMPAT

@@ -1,3 +0,0 @@
-.\" $FreeBSD$
-Set this option to omit the gnu extensions to grep from being included in
-BSD grep.

tools/build/options/WITH_GNU_GREP_COMPAT

@@ -1,4 +0,0 @@
-.\" $FreeBSD$
-Set this option to include GNU extensions in
-.Xr bsdgrep 1
-by linking against libgnuregex.

usr.bin/grep/Makefile

@@ -60,10 +60,7 @@ MLINKS+= grep.1 egrep.1 \
 	grep.1 rgrep.1
 .endif
 
-.if ${MK_GNU_GREP_COMPAT} != "no"
-CFLAGS+=	-DWITH_GNU_COMPAT
 LIBADD+=	regex
-.endif
 
 HAS_TESTS=
 SUBDIR.${MK_TESTS}+= tests

usr.bin/grep/grep.c

@@ -62,8 +62,7 @@ const char	*errstr[] = {
 /* 5*/	"\t[--context[=num]] [--directories=action] [--label] [--line-buffered]\n",
 /* 6*/	"\t[--null] [pattern] [file ...]\n",
 /* 7*/	"Binary file %s matches\n",
-/* 8*/	"%s (BSD grep) %s\n",
-/* 9*/	"%s (BSD grep, GNU compatible) %s\n",
+/* 8*/	"%s (BSD grep, GNU compatible) %s\n",
 };
 
 /* Flags passed to regcomp() and regexec() */
@@ -555,11 +554,7 @@ main(int argc, char *argv[])
 			filebehave = FILE_MMAP;
 			break;
 		case 'V':
-#ifdef WITH_GNU_COMPAT
-			printf(errstr[9], getprogname(), VERSION);
-#else
 			printf(errstr[8], getprogname(), VERSION);
-#endif
 			exit(0);
 		case 'v':
 			vflag = true;