Remove B_COMMON*_DIRECTORY and kCommon*Directory constants

* This does intentionally break source compatibility, so that a review
  of concerned code is forced.
* Binary compatibility should be maintained in most cases. The values
  of the constants for the writable directories are now used for the
  writable system directories. The values for the non-writable
  directories are mapped to "/boot/system/data/empty/...", an empty or
  non-existent directory, so that they will simply be skipped in search
  paths. Only code that explicitly expects to find something in a
  B_COMMON_* directory, will fail.

src/preferences/keymap/KeymapWindow.cpp

@@ -558,9 +558,10 @@ void
 KeymapWindow::_AddKeyboardLayouts(BMenu* menu)
 {
 	directory_which dataDirectories[] = {
+		B_USER_NONPACKAGED_DATA_DIRECTORY,
 		B_USER_DATA_DIRECTORY,
-		B_COMMON_DATA_DIRECTORY,
-		B_BEOS_DATA_DIRECTORY
+		B_SYSTEM_NONPACKAGED_DATA_DIRECTORY,
+		B_SYSTEM_DATA_DIRECTORY,
 	};
 
 	for (uint32 i = 0;