Delete talk directory, and references from build_ios_libs.sh.

BUG=webrtc:4256

Review-Url: https://codereview.webrtc.org/2296613002
Cr-Commit-Position: refs/heads/master@{#14040}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 00bcc3e..f07f49b 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -63,7 +63,6 @@
 # These directories should not be used but are maintained only to avoid breaking
 # some legacy downstream code.
 LEGACY_API_DIRS = (
-  'talk/app/webrtc',
   'webrtc/base',
   'webrtc/common_audio/include',
   'webrtc/modules/audio_coding/include',
@@ -459,6 +458,7 @@
                         ],
       pylintrc='pylintrc'))
 
+  # TODO(nisse): talk/ is no more, so make below checks simpler?
   # WebRTC can't use the presubmit_canned_checks.PanProjectChecks function since
   # we need to have different license checks in talk/ and webrtc/ directories.
   # Instead, hand-picked checks are included below.