travis: Fixedup gcc 5 error and allow gcc 6 to fail

.travis.yml

@@ -3,6 +3,8 @@ sudo: required
 dist: trusty
 
 matrix:
+    allow_failures:
+        compiler: gcc-6
     include:
         - os: linux
           compiler: gcc
@@ -73,9 +75,9 @@ matrix:
           osx_image: beta-xcode6.2
           compiler: gcc
           #Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
-#        - os: osx
-#          osx_image: beta-xcode6.3
-#          #
+        - os: osx
+          osx_image: beta-xcode6.3
+          #
         - os: osx
           osx_image: xcode6.4
           #Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn)

src/sdl/i_main.c

@@ -245,7 +245,7 @@ int main(int argc, char **argv)
 #endif
 
 	// return to OS
-#ifndef __GNUC__
+#if !defined (__GNUC__) || (__GNUC__ < 5)
 	return 0;
 #endif
 }