linux: add a use_gold flag that defaults to on
linux: add a use_gold flag that defaults to on

Currently, gyp attempts to autodetect whether the linker supports
the --icf flag.  It's more predictable to just require the caller
to specify whether they're using gold.

As a first demonstration of this, drop LINKER_USES_ICF code in the
Chrome build.  (I'll follow up with a gyp patch to remove the
LINKER_USES_ICF stuff in gyp.)


Review URL: http://codereview.chromium.org/9316110

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@121068 0039d316-1c4b-4281-b951-d872f2087c98

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