linux: use an in-tree copy of gold by default

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 161464c9237c8cf41af138d9243807263660b675..96431b511855489871974db4a1faee26fd91d7d9 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -601,6 +601,9 @@
     # Set to 1 to link against gsettings APIs instead of using dlopen().
     'linux_link_gsettings%': 0,
 
+    # Set to 0 to not use third_party/gold as the linker.
+    'linux_use_gold_binary%': 1,
+
     # Set Thumb compilation flags.
     'arm_thumb%': 0,
 
@@ -2000,6 +2003,16 @@
             'defines': ['KEEP_SHADOW_STACKS'],
             'cflags': ['-finstrument-functions'],
           }],
+          ['linux_use_gold_binary==1', {
+            'target_conditions': [
+              ['_toolset=="target"', {
+                'ldflags': [
+                  # Put our gold binary in the search path for the linker.
+                  '-Bthird_party/gold',
+                ],
+              }],
+            ],
+          }],
         ],
       },
     }],