BaseTools:Build cache cannot store the cache files for library package

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1867

Current build cache cannot store the cache for library package.
build -p MdePkg\MdePkg.dsc -a IA32 -b DEBUG -t VS2015x86 --hash
--binary-destination=BinCache
After build, the expected result is the BinCache folder is generated
and the MdePkg build cache files (e.g. .hash and .lib) are stored in
the BinCache folder. But the BinCache folder is not generated at all.

This patch is going to fix that issue.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Zhiju.Fan <zhijux.fan@intel.com>
Signed-off-by: Steven Shi <steven.shi@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/AutoGen/AutoGen.py

@@ -3569,8 +3569,11 @@ class ModuleAutoGen(AutoGen):
         if self.IsAsBuiltInfCreated:
             return
 
-        # Skip the following code for libraries
+        # Skip INF file generation for libraries
         if self.IsLibrary:
+            # Only store the library cache if needed
+            if GlobalData.gBinCacheDest:
+                self.CopyModuleToCache()
             return
 
         # Skip the following code for modules with no source files