Changed travis configuration to use gcc-5.
diff --git a/.travis.yml b/.travis.yml
index d347333..a8f1b35 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,15 +17,15 @@
   - BUILD_TYPE=Release VECTOR_COPY_ELISION_LEVEL=joinwithbinaryexpressions
 
 install:
-  - if [ "$VECTOR_COPY_ELISION_LEVEL" = "joinwithbinaryexpressions" ] && [ "$CC" = "gcc" ]; then
+  - if [ "$VECTOR_COPY_ELISION_LEVEL" = "joinwithbinaryexpressions" ] && [ "$CC" = "gcc" ] && [ "$BUILD_TYPE" = "Debug" ]; then
       export MAKE_JOBS=1;
     else
       export MAKE_JOBS=2;
     fi
   - export TEST_JOBS=2;
   - if [ "$CC" = "gcc" ]; then
-      export CC="gcc-4.9";
-      export CXX="g++-4.9";
+      export CC="gcc-5";
+      export CXX="g++-5";
     elif [ "$CC" = "clang" ]; then
       export CC="clang-3.7";
       export CXX="clang++-3.7";
@@ -72,8 +72,8 @@
       - ubuntu-toolchain-r-test
       - llvm-toolchain-precise-3.7
     packages:
-      - gcc-4.9
-      - g++-4.9
+      - gcc-5
+      - g++-5
       - clang-3.7
       - libprotobuf-dev
       - protobuf-compiler