Use -fuse-ld=gold when supported to select gold.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 68a4316b3c4bcfca9e46c1ed8e2f6f78e5f683b6..d1e7b8a4c5711a3a67c4200a399b80a268562ac3 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -3835,6 +3835,18 @@
                   }],
                 ],
               }],
+              # Newer gcc's support -fuse-ld, use the flag to force gold
+              # selection.
+              # gcc -- http://gcc.gnu.org/onlinedocs/gcc-4.8.0/gcc/Optimize-Options.html
+              # clang support -- http://clang-developers.42468.n3.nabble.com/Adding-fuse-ld-support-to-clang-td4032180.html

[Nico, 2014/04/10 21:27:19]

That link is just a thread where someone posted a patch for this option, but the
patch didn't go anywhere and isn't committed. Remove this line. (gcc_version
isn't set for clang, so this isn't used, which is fine.)

…but does third_party/gold (referenced a few lines below, I suppose it says
third_party/binutils at trunk) contain a ld.gold? Else gcc won't use the gold in
-B but the system one, rigth?

[mithro-old, 2014/04/11 02:17:56]

Actually the patch did land and then was reverted. The guy said he would update
the thread when he relands the patch. Changed the comment to be clearer.
---------------
The code was committed and reverted, so if you want to have a go at fixing the
tests, you'd be welcome.  Otherwise, I'll hopefully get back to it in a few
weeks (although it's further down the list than tidying up a load of MIPS back
end fixes for upstreaming).
---------------
Yes, it does say binutils at trunk. I have rebased this patch and uploaded.

third_party/binutils does contain an ld.gold

With this patch, you can use "linux_use_gold_flags=1" and
"linux_use_gold_binary=0" to use the system gold linker (when using gcc 4.8).

+              ['gcc_version>=48', {
+                'cflags': [
+                  '-fuse-ld=gold',
+                ],
+                'ldflags': [
+                  '-fuse-ld=gold',
+                ],
+              }]
             ],
           }],
           ['linux_use_gold_binary==1', {