Don't pass thumb-interwork to clang in the GN build.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/sysroot.gni")
 if (cpu_arch == "arm") {
   import("//build/config/arm.gni")
 }
 
@@ skipping 99 matching lines @@
         cflags += [
           "-march=$arm_arch",
           "-mfpu=$arm_fpu",
           "-mfloat-abi=$arm_float_abi",
         ]
         if (arm_tune != "") {
           cflags += "-mtune=$arm_tune"
         }
         if (arm_use_thumb) {
           cflags += [ "-mthumb" ]
-          if (is_android) {
+          if (is_android && !is_clang) {  # Clang doesn't support this option.
             cflags += [ "-mthumb-interwork" ]
           }
         }
       }
     }
 
     defines += [ "_FILE_OFFSET_BITS=64" ]
 
     # Omit unwind support in official builds to save space. We can use breakpad
     # for these builds.
@@ skipping 538 matching lines @@
   } else {
     cflags = [ "-g1" ]
   }
 }
 
 config("no_symbols") {
   if (!is_win) {
     cflags = [ "-g0" ]
   }
 }