https://trac.torproject.org/projects/tor/ticket/19001#comment:11
https://trac.torproject.org/projects/tor/ticket/19001#comment:21

Build libwebrtc using libcxx. Set use_custom_libcxx=0. According to the
source comment, use_custom_libcxx=1 means to use a precompiled libcxx in
the third_party directory.

Build the test target
obj/webrtc/api/test/peerconnection_unittests.fakeaudiocapturemodule.o
rather than peerconnection_unittests.isolated; building just an object
file doesn't require the linker and is faster.

Use x86_64-apple-darwin11-ar, not ar, to link libwebrtc-magic.a.
When linking go-webrtc later on, it would cause the error:
ld: warning: ignoring file lib/libwebrtc-darwin-amd64-magic.a, file was built for archive which is not the architecture being linked (x86_64)

Descriptions for each patch are in the mbox-formatted patch file.

Subject: [PATCH 01/13] Use flags for GNU grep, not BSD grep.
Subject: [PATCH 02/13] Remove flags not supported by Mac ld.
Subject: [PATCH 03/13] Undefine __APPLE__ in usrsctp.
Subject: [PATCH 04/13] Include <sys/socket.h> in macifaddrs_converter.cc.
Subject: [PATCH 05/13] Allow non-mac to build .m and .mm sources (objc and
Subject: [PATCH 06/13] Propagate "-framework Foundations" in ldflags.
Subject: [PATCH 07/13] Provide definitions of NS_ENUM and NS_OPTIONS.
Subject: [PATCH 08/13] Remove lightweight-generics annotations from NSArray
Subject: [PATCH 09/13] Use -fobjc-arc in webrtc/build/objc_common.gypi.
Subject: [PATCH 10/13] Replace firstObject with objectAtIndex:0.
Subject: [PATCH 11/13] fobjc-arc
Subject: [PATCH 12/13] Use objectAtIndex instead of array index syntax.
Subject: [PATCH 13/13] Hack out some more NS_ENUM and NS_OPTIONS.

As in ab1e5cffbf548f9f586b81928dc22ae90bdec374 for linux.

Update the "$(SDKROOT)" replacement command. Use our own $SDKROOT as the
replacement. Files are now found in additional subdirectories.