grep/pcre2: drop needless assignment + assert() on opt->pcre2

Drop an assignment added in b65abca (grep: use PCRE v2 for
optimized fixed-string search, 2019-07-01) and the overly cautious
assert() I added in 94da919 (grep: add support for PCRE v2,
2017-06-01).

There was never a good reason for this, it's just a relic from when I
initially wrote the PCREv2 support. We're not going to have confusion
about compile_pcre2_pattern() being called when it shouldn't just
because we forgot to cargo-cult this opt->pcre2 option.

Furthermore the "struct grep_opt" is (mostly) used for the options the
user supplied, let's avoid the pattern of needlessly assigning to it.

With my recent removal of the PCREv1 backend in 7599730 (Remove
support for v1 of the PCRE library, 2021-01-24) there's even less
confusion around what we call where in these codepaths, which is one
more reason to remove this.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

grep.c

@@ -373,8 +373,6 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	int patinforet;
 	size_t jitsizearg;
 
-	assert(opt->pcre2);
-
 	p->pcre2_compile_context = NULL;
 
 	/* pcre2_global_context is initialized in append_grep_pattern */
@@ -555,7 +553,6 @@ static void compile_regexp(struct grep_pat *p, struct grep_opt *opt)
 #endif
 	if (p->fixed || p->is_fixed) {
 #ifdef USE_LIBPCRE2
-		opt->pcre2 = 1;
 		if (p->is_fixed) {
 			compile_pcre2_pattern(p, opt);
 		} else {