CI/Travis: Change to gcc in an attempt to reduce the number of killed builds

.travis.yml

@@ -1,6 +1,6 @@
 language: cpp
 compiler:
-  - clang
+  - gcc
 
 git:
   depth: 1
@@ -18,6 +18,8 @@ install:
   - mysql -uroot -e 'create database test_mysql;'
   - mkdir bin
   - cd bin
+  - export CC=gcc-4.8
+  - export CXX=g++-4.8
   - cmake ../ -DWITH_WARNINGS=1 -DWITH_COREDEBUG=1 -DUSE_COREPCH=0 -DUSE_SCRIPTPCH=0 -DTOOLS=1 -DSCRIPTS=1 -DSERVERS=1 -DNOJEM=1 -DCMAKE_BUILD_TYPE=Release
 
 script: