grep/pcre2: correct reference to grep_init() in comment

Correct a comment added in 513f2b0 (grep: make PCRE2 aware of
custom allocator, 2019-10-16). This comment was never correct in
git.git, but was consistent with an older version of the patch[1].

1. https://lore.kernel.org/git/[email protected]/

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

Author: avar

grep.c

@@ -373,7 +373,7 @@ static void compile_pcre2_pattern(struct grep_pat *p, const struct grep_opt *opt
 	int patinforet;
 	size_t jitsizearg;
 
-	/* pcre2_global_context is initialized in append_grep_pattern */
+	/* pcre2_global_context is initialized in grep_init */
 	if (opt->ignore_case) {
 		if (!opt->ignore_locale && has_non_ascii(p->pattern)) {
 			if (!pcre2_global_context)