Fix inclusion of config.h, when I was writing this I added a relative path directly to acconf.h

Originally committed to SVN as r5316.

aegisub/libaegisub/unix/path.cpp

@@ -18,11 +18,16 @@
 /// @brief Common paths.
 /// @ingroup libaegisub
 
-#include "../commit/acconf.h"
 
+#include "config.h"
+
+#ifndef LAGI_PRE
 #include <string>
+#endif
+
 #include <libaegisub/path.h>
 
+
 namespace agi {
 
 const std::string Path::Data() {