GN(android) Don't enable --gc-sections in debug mode.

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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/ccache.gni")
 
@@ skipping 1141 matching lines @@
     # On Android we kind of optimize some things that don't affect debugging
     # much even when optimization is disabled to get the binary size down.
     cflags = [
       "-Os",
       "-fdata-sections",
       "-ffunction-sections",
     ]
     if (!using_sanitizer) {
       cflags += [ "-fomit-frame-pointer" ]
     }
-    ldflags = common_optimize_on_ldflags
+
+    # Don't use gc-sections since it can cause links to succeed when they
+    # actually shouldn't. http://crbug.com/159847
+    ldflags = common_optimize_on_ldflags - [ "-Wl,--gc-sections" ]
   } else {
     cflags = [ "-O0" ]
     ldflags = []
   }
 }
 
 # Turns up the optimization level. On Windows, this implies whole program
 # optimization and link-time code generation which is very expensive and should
 # be used sparingly.
 config("optimize_max") {
@@ skipping 121 matching lines @@
   if (symbol_level == 0) {
     configs = [ ":no_symbols" ]
   } else if (symbol_level == 1) {
     configs = [ ":minimal_symbols" ]
   } else if (symbol_level == 2) {
     configs = [ ":symbols" ]
   } else {
     assert(false)
   }
 }