Allow users to disable SVN update.

This commit adds the NOUPGIT=1 to the SVN load routine,
which allows users to prevent updating any SVN repos.
This option must be passed via the ENV.
Add seperate targets for linux 32/64 bit
Use -Wall in non-debug mode too
Set CFLAGS for enet compile
Fix 32/64 bit detection in native target
Fix run script for linux/UNIX