Remove mentions to xcode_clang which has been removed.

It has been removed upstream by
https://chromium-review.googlesource.com/c/chromium/src/+/3268669.

Bug: None
Change-Id: Ib4dca3322d0a526fea739c7dc3dccd2fc132ec17
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/238422
Reviewed-by: Christoffer Jansson <jansson@google.com>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35383}

BUILD.gn

@@ -352,21 +352,10 @@ config("common_config") {
         "-Wundef",
       ]
 
-      # use_xcode_clang only refers to the iOS toolchain, host binaries use
-      # chromium's clang always.
-      if (!is_nacl &&
-          (!use_xcode_clang || current_toolchain == host_toolchain)) {
-        # Flags NaCl (Clang 3.7) and Xcode 7.3 (Clang clang-703.0.31) do not
-        # recognize.
+      if (!is_nacl) {
+        # Flags NaCl (Clang 3.7) do not recognize.
         cflags += [ "-Wunused-lambda-capture" ]
       }
-
-      if (use_xcode_clang) {
-        # This may be removed if the clang version in xcode > 12.4 includes the
-        # fix https://reviews.llvm.org/D73007.
-        # https://bugs.llvm.org/show_bug.cgi?id=44556
-        cflags += [ "-Wno-range-loop-analysis" ]
-      }
     }
 
     if (is_win && !is_clang) {