GN: Fix error in is_component_build in boringssl

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" ]
 }
 
@@ skipping 53 matching lines @@
     defines += [ "OPENSSL_NO_ASM" ]
   }
 
   if (is_component_build) {
     if (!is_win) {
       configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
     }
     if (is_posix && !is_mac) {
       # Avoid link failures on Linux x86-64.
       # See http://rt.openssl.org/Ticket/Display.html?id=2466&user=guest&pass=guest
-      ldflags += [ "-Wl,-Bsymbolic" ]
+      ldflags = [ "-Wl,-Bsymbolic" ]
     }
   }
 }