Fix for running 'python -m' when using swig -builtin

Same as e05b5ea for -builtin.

Also added runtime tests to check 'python -m'.

Examples/python/import_packages/same_modnames2/runme.py

@@ -1,4 +1,6 @@
 import os.path
+import subprocess
+import sys
 
 testname = os.path.basename(os.path.dirname(os.path.abspath(__file__)))
 print "Testing " + testname + " - %module(package=...) + python 'import' in __init__.py"
@@ -12,3 +14,7 @@ classname = str(type(var2))
 if classname.find("pkg1.pkg2.foo.Pkg2_Foo") == -1:
     raise RuntimeError("failed type checking: " + classname)
 print "  Successfully created object pkg1.pkg2.foo.Pkg2_Foo"
+
+commandline = sys.executable + " -m pkg1.pkg2.foo"
+subprocess.check_call(commandline, shell=True)
+print("  Finished running: " + commandline)