Add #pragma once to the top of a couple of the most commonly included headers in build/include. DONT_BUILD.

git-svn-id: https://svn.eduke32.com/eduke32@5664 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/build/include/baselayer.h

@@ -2,6 +2,8 @@
 // for the Build Engine
 // by Jonathon Fowler (jf@jonof.id.au)
 
+#pragma once
+
 #ifndef baselayer_h_
 #define baselayer_h_
 

polymer/eduke32/build/include/build.h

@@ -5,6 +5,7 @@
 // This file has been modified from Ken Silverman's original release
 // by Jonathon Fowler (jf@jonof.id.au)
 
+#pragma once
 
 #ifndef build_h_
 #define build_h_

polymer/eduke32/build/include/compat.h

@@ -2,6 +2,8 @@
 // certain build environments. It also levels the playing field caused
 // by different platforms.
 
+#pragma once
+
 #ifndef compat_h_
 #define compat_h_