Geanyprj: fix memory leak, fix false positive

This leak was found by cppcheck. `config` was freed twice but didn't freed in function body:)

There is also false positive I think:
```
// memleak:utils.c:72
	v = g_strsplit_set(filename, "/\\", -1);
	if (!g_strv_length(v))
		return g_strdup("."); // possible leak
```
g_strv_length should be zero only if v is NULL, right? Otherwise this is a leak. Anyway only author can understand this pointer magic.