global: make 'char *path' const where possible

Signed-off-by: Christian Hesse <mail@eworm.de>
diff --git a/ui-summary.c b/ui-summary.c
index 8e81ac4..947812a 100644
--- a/ui-summary.c
+++ b/ui-summary.c
@@ -99,7 +99,7 @@
 	return full_path;
 }
 
-void cgit_print_repo_readme(char *path)
+void cgit_print_repo_readme(const char *path)
 {
 	char *filename, *ref, *mimetype;
 	int free_filename = 0;