Fixup coverage build

BUILD.gn

 # Copyright 2016 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("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_common_config") {
   cflags = []
+  ldflags = []
   include_dirs = [
     ".",
     "third_party/freetype/include",
     "third_party/freetype/include/freetype",
   ]
   defines = [
     "OPJ_STATIC",
     "PNG_PREFIX",
     "PNG_USE_READ_MACROS",
   ]
@@ skipping 10 matching lines @@
     defines += [ "PDF_ENABLE_V8" ]
   }
 
   if (pdf_enable_xfa) {
     defines += [ "PDF_ENABLE_XFA" ]
   }
 
   if (pdf_use_win32_gdi) {
     defines += [ "PDFIUM_PRINT_TEXT_WITH_GDI" ]
   }
+
+  if (use_coverage && is_clang) {
+    cflags += [
+      "--coverage",
+      "-g",
+      "-O0",
+    ]
+    ldflags += [ "--coverage" ]
+  }
 }
 
 config("pdfium_core_config") {
   cflags = []
-  ldflags = []
   configs = [ ":pdfium_common_config" ]
   defines = [ "V8_DEPRECATION_WARNINGS" ]
   if (is_linux) {
     if (current_cpu == "x64") {
       defines += [ "_FX_CPU_=_FX_X64_" ]
       cflags += [ "-fPIC" ]
     } else if (current_cpu == "x86") {
       defines += [ "_FX_CPU_=_FX_X86_" ]
     }
   }
   if (is_win) {
     cflags += [ "/wd4267" ]
   }
-  if (use_coverage && is_clang) {
-    cflags += [
-      "--coverage",
-      "-g",
-      "-O0",
-    ]
-    ldflags += [ "--coverage" ]
-  }
 }
 
 config("xfa_warnings") {
   visibility = [ ":*" ]
   if (is_posix && !is_clang) {  # When GCC.
     cflags = [ "-Wno-strict-overflow" ]
   }
 }
 
 static_library("pdfium") {
@@ skipping 1794 matching lines @@
       "//samples",
     ]
   }
   group("fuzzers") {
     testonly = true
     deps = [
       "//testing/libfuzzer",
     ]
   }
 }