Core: Remove MemoryWatcher

MemoryWatcher only works on Linux and affects emulation determinism due
to scheduling additional events, which causes NetPlay to desync.
Considering that this interface is a rather specialized use case, the
communication with it is kinda crappy *and* it's affecting emulation, I
think it's best to just axe it and come up with a better implementation
of the functionality.

Source/Core/Common/FileUtil.h

@@ -48,7 +48,6 @@ enum
   D_THEMES_IDX,
   D_STYLES_IDX,
   D_PIPES_IDX,
-  D_MEMORYWATCHER_IDX,
   D_WFSROOT_IDX,
   D_BACKUP_IDX,
   D_RESOURCEPACK_IDX,
@@ -64,8 +63,6 @@ enum
   F_ARAMDUMP_IDX,
   F_FAKEVMEMDUMP_IDX,
   F_GCSRAM_IDX,
-  F_MEMORYWATCHERLOCATIONS_IDX,
-  F_MEMORYWATCHERSOCKET_IDX,
   F_WIISDCARD_IDX,
   NUM_PATH_INDICES
 };