buildreport_parser.py: Properly handle NULL libraries (#671)

Currently, buildreport_parser maintains a dictionary of library classes.

This fails for NULL libraries. If more than one NULL library exists, only the last instance encountered will be in the dictionary.

To match edk2 build tool behavior, NULL libraries will have an instance number appened to the name.

i.e. NULL0, NULL1, etc

edk2toollib/uefi/edk2/parsers/buildreport_parser.py

@@ -40,6 +40,7 @@ def __init__(self, content: str, ws: str, packagepatahlist: list, pathconverter:
         self.Type = ""
         self.PCDs = {}
         self.Libraries = {}
+        self.NullLibraryCount = 0
         self.Depex = ""
         self.WorkspacePath = ws
         self.PackagePathList = packagepatahlist
@@ -118,6 +119,10 @@ def Parse(self) -> None:
                         lib_class = templine.partition("{")[2].partition("}")[0].partition(":")[0].strip()
                         lib_instance = templine.partition("{")[0].strip()
 
+                        if lib_class.strip().lower() == "null":
+                            lib_class += str(self.NullLibraryCount)
+                            self.NullLibraryCount += 1
+
                         # Take absolute path and convert to EDK build path
                         RelativePath = self.pathConverter.GetEdk2RelativePathFromAbsolutePath(lib_instance)
                         if RelativePath is not None: