GN: Make content_shell and webkit_unit_tests work in component build

third_party/boringssl/BUILD.gn

 # Copyright 2014 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.
 
 # Config for us and everybody else depending on BoringSSL.
 config("openssl_config") {
   include_dirs = []
   include_dirs += [ "src/include" ]
   if (is_component_build) {
-    defines += [
+    defines = [
       "BORINGSSL_SHARED_LIBRARY",
     ]
   }
 }
 
 # Config internal to this build file.
 config("openssl_internal_config") {
   visibility = ":*"  # Only targets in this file can depend on this.
 }
 
@@ skipping 46 matching lines @@
       sources += gypi_values.boringssl_linux_x86_sources
     } else {
       defines += [ "OPENSSL_NO_ASM" ]
     }
   } else if (cpu_arch == "arm") {
     sources += gypi_values.boringssl_linux_arm_sources
   } else {
     defines += [ "OPENSSL_NO_ASM" ]
   }
 }