Split up Carthage job by platform

Author: mdiep

.travis.yml

@@ -56,9 +56,27 @@ matrix:
     - script:
         - brew update
         - brew outdated carthage || brew upgrade carthage
-        - carthage build --no-skip-current
+        - carthage build --no-skip-current --platform mac
       env:
-        - JOB=CARTHAGE
+        - JOB=CARTHAGE-macOS
+    - script:
+        - brew update
+        - brew outdated carthage || brew upgrade carthage
+        - carthage build --no-skip-current --platform iOS
+      env:
+        - JOB=CARTHAGE-iOS
+    - script:
+        - brew update
+        - brew outdated carthage || brew upgrade carthage
+        - carthage build --no-skip-current --platform tvOS
+      env:
+        - JOB=CARTHAGE-tvOS
+    - script:
+        - brew update
+        - brew outdated carthage || brew upgrade carthage
+        - carthage build --no-skip-current --platform watchOS
+      env:
+        - JOB=CARTHAGE-watchOS
     - os: osx
       language: generic
       script: swift build