Do not use bundled gold when using GCC LTO.

This is because GCC also uses the -B search path at link time to find
"as", and our bundled "as" can only target x86. See also the discussion at
https://codereview.chromium.org/1084133002/

(I also tried adding this condition around line 858, but this won't work
because of scoping issues ("clang" is not defined here)).

R=thakis@chromium.org,fdegans@chromium.org
BUG=469376

Review URL: https://codereview.chromium.org/1096553002

Cr-Commit-Position: refs/heads/master@{#325545}

build/common.gypi

@@ -4535,11 +4535,16 @@
               '-B<!(cd <(DEPTH) && pwd -P)/<(binutils_dir)',
             ],
           }],
-          ['linux_use_bundled_gold==1', {
+          ['linux_use_bundled_gold==1 and '
+           'not (clang==0 and (use_lto==1 or use_lto_o2==1))', {
             # Put our binutils, which contains gold in the search path. We pass
             # the path to gold to the compiler. gyp leaves unspecified what the
             # cwd is when running the compiler, so the normal gyp path-munging
             # fails us. This hack gets the right path.
+            #
+            # Disabled when using GCC LTO because GCC also uses the -B search
+            # path at link time to find "as", and our bundled "as" can only
+            # target x86.
             'ldflags': [
               '-B<!(cd <(DEPTH) && pwd -P)/<(binutils_dir)',
             ],