Stop building 'all' in chromium.webrtc.fyi / Mac

This should fix the builder.
And there's no good reason to build all if chromium.webrtc doesn't.

Bug: chromium:820041
TBR: machenbach@chromium.org
No-Try: True
Change-Id: Id581397d0c1821dd17a0b76df540128ad71028ab
Reviewed-on: https://chromium-review.googlesource.com/955683
Commit-Queue: Oleh Prypin <oprypin@chromium.org>
Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541878}

testing/buildbot/chromium.webrtc.fyi.json

@@ -34,12 +34,17 @@
   },
   "Mac Builder": {
     "additional_compile_targets": [
-      "all"
+      "browser_tests",
+      "capture_unittests",
+      "content_browsertests",
+      "content_unittests",
+      "frame_analyzer",
+      "jingle_unittests",
+      "remoting_unittests"
     ]
   },
   "Mac Builder (dbg)": {
     "additional_compile_targets": [
-      "all",
       "browser_tests",
       "capture_unittests",
       "content_browsertests",

testing/buildbot/waterfalls.pyl

@@ -1969,12 +1969,17 @@
       },
       'Mac Builder': {
         'additional_compile_targets': [
-          'all',
+          'browser_tests',
+          'capture_unittests',
+          'content_browsertests',
+          'content_unittests',
+          'frame_analyzer',
+          'jingle_unittests',
+          'remoting_unittests',
         ],
       },
       'Mac Builder (dbg)': {
         'additional_compile_targets': [
-          'all',
           'browser_tests',
           'capture_unittests',
           'content_browsertests',