- Fixed miscompilation with Clang 3.5.0.

The optimizer miscompiles the function FBehavior::LoadScriptsDirectory and causes random crashes when zdoom is run with wads containing scripts.
As said in the comment, I just hope that the Clang devs fix it for the next patching release, ie 3.5.1.
Allow SXF_SETMASTER to work on non-monsters.
Merge branch 'clang_3_5_crash' of https://github.com/edward-san/zdoom
Merge branch 'setmasterfix' of https://github.com/MajorCooke/zdoom