bisect: add git_path_bisect_terms helper

This avoids using the dangerous git_path(). Right now
there's only one call site (because the writing half is
still part of the shell script), but it may come in handy in
the future as more of bisect is written in C. It also
matches how we access the other BISECT_* files.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: peff

bisect.c

@@ -430,6 +430,7 @@ static int read_bisect_refs(void)
 
 static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
 static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
+static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
 
 static void read_bisect_paths(struct argv_array *array)
 {
@@ -905,7 +906,7 @@ static void show_diff_tree(const char *prefix, struct commit *commit)
 void read_bisect_terms(const char **read_bad, const char **read_good)
 {
 	struct strbuf str = STRBUF_INIT;
-	const char *filename = git_path("BISECT_TERMS");
+	const char *filename = git_path_bisect_terms();
 	FILE *fp = fopen(filename, "r");
 
 	if (!fp) {