Merge pull request #306 from apple/update-swift-5-branch

Update swift-5.0-branch config to checkout new branches

Author: shahmishal

common.py

@@ -62,13 +62,13 @@
         'clang': 'swift-5.0-branch',
         'compiler-rt': 'swift-5.0-branch',
         'swift': 'swift-5.0-branch',
-        'cmark': 'master',
+        'cmark': 'swift-5.0-branch',
         'ninja': 'release',
-        'llbuild': 'master',
-        'swiftpm': 'master',
-        'swift-corelibs-libdispatch': 'master',
-        'swift-corelibs-foundation': 'master',
-        'swift-corelibs-xctest': 'master',
+        'llbuild': 'swift-5.0-branch',
+        'swiftpm': 'swift-5.0-branch',
+        'swift-corelibs-libdispatch': 'swift-5.0-branch',
+        'swift-corelibs-foundation': 'swift-5.0-branch',
+        'swift-corelibs-xctest': 'swift-5.0-branch',
     },
     'swift-4.0-branch': {
         'llvm': 'swift-4.0-branch',