dds/etc1/pbm/pvr: Make those modules and split thirdparty files

They are not particularly packaged in Linux distros so we do not
facilitate unbundling via SCons. There could be done if/when there
is interest.

Also s/pnm/pbm/, long-lived typo :)

modules/dds/config.py

@@ -0,0 +1,6 @@
+
+def can_build(platform):
+	return True
+
+def configure(env):
+	pass