BaseTools: Remove the logic SourceOverridePath

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1350
SOURCE_OVERRIDE_PATH is for EDK component INF files.
The corresponding logic should be removed.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Common/GlobalData.py

@@ -29,7 +29,6 @@ gPlatformOtherPcds = {}
 gActivePlatform = None
 gCommandLineDefines = {}
 gEdkGlobal = {}
-gOverrideDir = {}
 gCommandMaxLength = 4096
 # for debug trace purpose when problem occurs
 gProcessingFile = ''