travis: don't run full testsuite with gcc-4.8

Build test (non-developer) is probably enough.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

.travis.yml

@@ -17,7 +17,7 @@ env:
   - VALGRIND=1 ARCH=64 DEVELOPER=0 COMPILER=gcc TEST_GROUP=2 TEST_GROUP_COUNT=3 SOURCE_CHECK_ONLY=false
   - VALGRIND=1 ARCH=64 DEVELOPER=0 COMPILER=gcc TEST_GROUP=3 TEST_GROUP_COUNT=3 SOURCE_CHECK_ONLY=false
   - VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=clang SOURCE_CHECK_ONLY=false
-  - VALGRIND=0 ARCH=64 DEVELOPER=1 COMPILER=gcc-4.8 SOURCE_CHECK_ONLY=false
+  - VALGRIND=0 ARCH=64 DEVELOPER=0 COMPILER=gcc-4.8 SOURCE_CHECK_ONLY=true
   - VALGRIND=1 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=1 TEST_GROUP_COUNT=6 SOURCE_CHECK_ONLY=false
   - VALGRIND=1 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=2 TEST_GROUP_COUNT=6 SOURCE_CHECK_ONLY=false
   - VALGRIND=1 ARCH=64 DEVELOPER=1 COMPILER=gcc TEST_GROUP=3 TEST_GROUP_COUNT=6 SOURCE_CHECK_ONLY=false