BaseTool: Add cache for the result of SkipAutogen.

Add a cache for the value of skip ModuleAutoGen
process flag. This cache can improve build performance.

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

@@ -113,3 +113,4 @@ gPlatformHash = None
 gPackageHash = {}
 gModuleHash = {}
 gEnableGenfdsMultiThread = False
+gSikpAutoGenCache = set()