Temporarily disable s390x job

These aren't getting scheduled and just keep hogging jobs so
nothing else gets scheduled either.

Author: nikic

.travis.yml

@@ -74,8 +74,8 @@ jobs:
           arch: amd64
         - env: ENABLE_ZTS=1 ENABLE_DEBUG=1 SKIP_IO_CAPTURE_TESTS=1 ARM64=1
           arch: arm64
-        - env: ENABLE_ZTS=1 ENABLE_DEBUG=1 SKIP_IO_CAPTURE_TESTS=1 S390X=1
-          arch: s390x
+        #- env: ENABLE_ZTS=1 ENABLE_DEBUG=1 SKIP_IO_CAPTURE_TESTS=1 S390X=1
+        # arch: s390x
 
 before_script:
     - ccache --version