Don't use all_dependent_configs for sdk frameworks

libs should be propagated to the final binary even without that:
https://gn.googlesource.com/gn/+/master/docs/reference.md#var_libs

But add some missing SDK framework dependencies:

* RTCNativeI420Buffer.mm uses CGBitmapContextGetBytesPerRow.
* socketrocket uses SecCertificateCopyData.

Bug: None
Change-Id: Iba38a5dfaf470a5a790d494cbec8ade44b1d16ba
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/146082
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28605}

examples/BUILD.gn

@@ -583,6 +583,7 @@ if (is_ios || (is_mac && target_cpu != "x86")) {
 
     libs = [
       "CFNetwork.framework",
+      "Security.framework",
       "icucore",
     ]
   }