Keep building RocksJava on all architectures (#6583)

Summary:
Adding solid support for multiple architectures was initially triggered by RocksJava users. As such I would like to keep the CI for RocksJava on all architectures, to ensure we don't break backwards compatibility.

pdillinger okay let's see how long it takes to complete Travis-CI with this one...
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6583

Reviewed By: cheng-chang

Differential Revision: D21036718

Pulled By: pdillinger

fbshipit-source-id: 97afe0db2e4c575cc0284fdc1d4cc45d5deb2272

.travis.yml

@@ -121,14 +121,14 @@ matrix:
     os: linux
     arch: ppc64le
     env: TEST_GROUP=4
-  - if: type = pull_request
+  - if: type = pull_request AND commit_message !~ /java/
     os : osx
     env: JOB_NAME=java_test
-  - if: type = pull_request
+  - if: type = pull_request AND commit_message !~ /java/
     os : linux
     arch: arm64
     env: JOB_NAME=java_test
-  - if: type = pull_request
+  - if: type = pull_request AND commit_message !~ /java/
     os: linux
     arch: ppc64le
     env: JOB_NAME=java_test