Fix uninitialized var warnings

src/index.c

@@ -1345,7 +1345,7 @@ static size_t read_extension(git_index *index, const char *buffer, size_t buffer
 static int parse_index(git_index *index, const char *buffer, size_t buffer_size)
 {
 	unsigned int i;
-	struct index_header header;
+	struct index_header header = { 0 };
 	git_oid checksum_calculated, checksum_expected;
 
 #define seek_forward(_increase) { \

src/revparse.c

@@ -16,7 +16,7 @@
 
 static int disambiguate_refname(git_reference **out, git_repository *repo, const char *refname)
 {
-	int error, i;
+	int error = 0, i;
 	bool fallbackmode = true;
 	git_reference *ref;
 	git_buf refnamebuf = GIT_BUF_INIT, name = GIT_BUF_INIT;

tests-clar/repo/iterator.c

@@ -422,7 +422,7 @@ static void build_test_tree(
 	git_treebuilder *builder;
 	const char *scan = fmt, *next;
 	char type, delimiter;
-	git_filemode_t mode;
+	git_filemode_t mode = GIT_FILEMODE_BLOB;
 	git_buf name = GIT_BUF_INIT;
 	va_list arglist;