Add new API find_path[s](), find_path_for_path()

The new functions are meant to replace many uses of find_directory():
* find_paths() is supposed to be used when the directories of a certain
  kind in all installation directories are needed (e.g. font
  directories, add-on directory, etc.). Using this API makes code
  robust wrt addition or removal of installation locations.
* find_path() is supposed to be used when files/directories associated
  with a loaded program, library, or add-on need to be found (e.g. data
  files or global settings).
* find_path_for_path() is similar to find_path(), but it starts from a
  given path instead of an image.

headers/private/system/find_directory_private.h

@@ -17,6 +17,17 @@ __BEGIN_DECLS
 status_t __find_directory(directory_which which, dev_t device, bool createIt,
 	char *returnedPath, int32 pathLength);
 
+status_t __find_path(const void* codePointer, const char* dependency,
+	path_base_directory baseDirectory, const char* subPath, uint32 flags,
+	char* pathBuffer, size_t bufferSize);
+
+status_t __find_path_for_path(const char* path, const char* dependency,
+	path_base_directory baseDirectory, const char* subPath, uint32 flags,
+	char* pathBuffer, size_t bufferSize);
+
+status_t __find_paths(path_base_directory baseDirectory, const char* subPath,
+	uint32 flags, char*** _paths, size_t* _pathCount);
+
 
 __END_DECLS