pickaxe: rename variables in has_changes() for brevity

Rename the {one,two}_contains variables to c{1,2}. This will make a
follow-up change easier to read.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-pickaxe.c

@@ -108,9 +108,9 @@ static int has_changes(mmfile_t *one, mmfile_t *two,
 		       struct diff_options *o,
 		       regex_t *regexp, kwset_t kws)
 {
-	unsigned int one_contains = one ? contains(one, regexp, kws) : 0;
+	unsigned int c1 = one ? contains(one, regexp, kws) : 0;
-	unsigned int two_contains = two ? contains(two, regexp, kws) : 0;
+	unsigned int c2 = two ? contains(two, regexp, kws) : 0;
-	return one_contains != two_contains;
+	return c1 != c2;
 }
 
 static int pickaxe_match(struct diff_filepair *p, struct diff_options *o,