commit: fix cast warnings

/home/kas/git/public/libgit2/src/commit.c: In function ‘commit_parse_buffer’:
/home/kas/git/public/libgit2/src/commit.c:186:23: warning: cast discards ‘__attribute__((const))’ qualifier from pointer target type [-Wcast-qual]
/home/kas/git/public/libgit2/src/commit.c:187:27: warning: cast discards ‘__attribute__((const))’ qualifier from pointer target type [-Wcast-qual]

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>

src/commit.c

@@ -183,8 +183,8 @@ cleanup:
 
 int commit_parse_buffer(git_commit *commit, const void *data, size_t len)
 {
-	const char *buffer = (char *)data;
-	const char *buffer_end = (char *)data + len;
+	const char *buffer = data;
+	const char *buffer_end = (const char *)data + len;
 
 	git_oid parent_oid;
 	int error;