makepanda: Always use /BIGOBJ when compiling with Eigen

Anything from pgraph onward needs it due to the size of Eigen, but let's just always pass it so we don't constantly have to chase compiler errors

makepanda/makepanda.py

@@ -1241,7 +1241,7 @@ def CompileCxx(obj,src,opts):
             if (building):
                 cmd += " /DBUILDING_" + building
 
-            if ("BIGOBJ" in opts) or GetTargetArch() == 'x64':
+            if ("BIGOBJ" in opts) or GetTargetArch() == 'x64' or not PkgSkip("EIGEN"):
                 cmd += " /bigobj"
 
             cmd += " /Zm300"