Exclude more Travis builds for each pull request (#6557)

Summary:
On recently adding ARM64 and PPC64LE builds to Travis, we
seem to have hit some parallel build limits that dramatically increased
queue times.

This change majorly limits the configurations for ARM64 and PPC64LE to
build on each pull request, but keeps the large matrix for branch
builds.

In the process, I changed some previously excluded osx build configurations
to happen in branch builds.

NB: we might want to move master branch Travis build to daily trigger
rather than push trigger to further reduce contention.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6557

Test Plan: Travis only

Reviewed By: siying

Differential Revision: D20524575

Pulled By: pdillinger

fbshipit-source-id: babcb2c64e195679e472473a1cbdf42de47231ff

.travis.yml

@@ -54,14 +54,6 @@ env:
 
 matrix:
   exclude:
-  - os: osx
-    env: TEST_GROUP=1
-  - os: osx
-    env: TEST_GROUP=2
-  - os: osx
-    env: TEST_GROUP=3
-  - os: osx
-    env: TEST_GROUP=4
   - os: osx
     env: JOB_NAME=cmake-gcc8
   - os: osx
@@ -78,6 +70,83 @@ matrix:
     env: JOB_NAME=cmake-mingw
   - os: linux
     compiler: clang
+  # Exclude most osx, arm64 and ppc64le tests for pull requests, but build in branches
+  - if: type != pull_request
+    os: osx
+    env: TEST_GROUP=1
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: TEST_GROUP=1
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: TEST_GROUP=1
+  - if: type != pull_request
+    os: osx
+    env: TEST_GROUP=2
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: TEST_GROUP=2
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: TEST_GROUP=2
+  - if: type != pull_request
+    os: osx
+    env: TEST_GROUP=3
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: TEST_GROUP=3
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: TEST_GROUP=3
+  - if: type != pull_request
+    os: osx
+    env: TEST_GROUP=4
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: TEST_GROUP=4
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: TEST_GROUP=4
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: JOB_NAME=java-test
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: JOB_NAME=java-test
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: JOB_NAME=lite-build
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: JOB_NAME=lite-build
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: JOB_NAME=examples
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: JOB_NAME=examples
+  - if: type != pull_request
+    os : linux
+    arch: arm64
+    env: JOB_NAME=cmake-gcc8
+  - if: type != pull_request
+    os: linux
+    arch: ppc64le
+    env: JOB_NAME=cmake-gcc8
 
 install:
   - if [ "${TRAVIS_OS_NAME}" == osx ]; then