grep: fix NO_LIBPCRE1_JIT to fully disable JIT

If you have a pcre1 library which is compiled with JIT enabled then
PCRE_STUDY_JIT_COMPILE will be defined whether or not the
NO_LIBPCRE1_JIT configuration is set.

This means that we enable JIT functionality when calling pcre_study
even if NO_LIBPCRE1_JIT has been explicitly set and we just use plain
pcre_exec later.

Fix this by using own macro (GIT_PCRE_STUDY_JIT_COMPILE) which we set to
PCRE_STUDY_JIT_COMPILE only if NO_LIBPCRE1_JIT is not set and define to
0 otherwise, as before.
Reviewed-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

grep.c

@@ -380,7 +380,7 @@ static void compile_pcre1_regexp(struct grep_pat *p, const struct grep_opt *opt)
 	if (!p->pcre1_regexp)
 		compile_regexp_failed(p, error);
 
-	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, PCRE_STUDY_JIT_COMPILE, &error);
+	p->pcre1_extra_info = pcre_study(p->pcre1_regexp, GIT_PCRE_STUDY_JIT_COMPILE, &error);
 	if (!p->pcre1_extra_info && error)
 		die("%s", error);
 

grep.h

@@ -7,11 +7,12 @@
 #if PCRE_MAJOR >= 8 && PCRE_MINOR >= 32
 #ifndef NO_LIBPCRE1_JIT
 #define GIT_PCRE1_USE_JIT
+#define GIT_PCRE_STUDY_JIT_COMPILE PCRE_STUDY_JIT_COMPILE
 #endif
 #endif
 #endif
-#ifndef PCRE_STUDY_JIT_COMPILE
-#define PCRE_STUDY_JIT_COMPILE 0
+#ifndef GIT_PCRE_STUDY_JIT_COMPILE
+#define GIT_PCRE_STUDY_JIT_COMPILE 0
 #endif
 #if PCRE_MAJOR <= 8 && PCRE_MINOR < 20
 typedef int pcre_jit_stack;