Travis testing always fails since we moved to gcc-8. This is due to a bug in

the x86 host gcc-4.8 which miscompiles gcc-8.  Switching to gcc-6 to fix it.

.travis.yml

@@ -23,12 +23,12 @@ addons:
       - libtool
       - patchutils
       - texinfo
-      - gcc-4.8
-      - g++-4.8
+      - gcc-6
+      - g++-6
 before_install:
   - export MAKEFLAGS="-j3"
-  - export CXX=g++-4.8
-  - export CC=gcc-4.8
+  - export CXX=g++-6
+  - export CC=gcc-6
 env:
 #  - CARGS="--enable-linux  --disable-multilib --with-arch=rv32imac --with-abi=ilp32"
 #  - CARGS="--enable-linux  --disable-multilib --with-arch=rv32imafdc --with-abi=ilp32"