Removing EXPAT_RELATIVE_PATH and rtc_relative_path

webrtc/webrtc.gni

Index: webrtc/webrtc.gni
diff --git a/webrtc/webrtc.gni b/webrtc/webrtc.gni
index 72e031ee7723a04da808af580f4d492cd53e8d7a..af4d6f97dbbc12d25a24f18755298e270d2fe0f2 100644
--- a/webrtc/webrtc.gni
+++ b/webrtc/webrtc.gni
@@ -43,9 +43,6 @@ declare_args() {
   # Enable this to let the Opus audio codec change complexity on the fly.
   rtc_opus_variable_complexity = false
 
-  # Disable to use absolute header paths for some libraries.
-  rtc_relative_path = true
-
   # Used to specify an external Jsoncpp include path when not compiling the
   # library that comes with WebRTC (i.e. rtc_build_json == 0).
   rtc_jsoncpp_root = "//third_party/jsoncpp/source/include"