GN: pass -Wl,--disable-new-dtags on linux so DT_RPATH works

GN: pass -Wl,--disable-new-dtags on linux so DT_RPATH works

Without this shared library dependencies that should be resolved via
rpath remain unresolved and component build libraries don't run. Copied
from build/common.gypi which is conditional on binutils version, but I'm
pretty sure the GN build never runs on older binutils.

R=brettw@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=286399

[jamesr, 2014-07-29 01:09:57]

Tested by doing an is_component_build = true build and comparing 'ldd
out_gn/Component/net_unittests' with and without this patch. Without it,
libv8.so et all (which are transitively but not directly dependended on by
net_unittests) are unresolved, with it they resolve to
out_gn/Component/lib/libv8.so etc

[brettw, 2014-07-29 20:39:39]

lgtm

[jamesr, 2014-07-29 22:13:13]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-07-29 22:14:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jamesr@chromium.org/428753003/1

[commit-bot: I haz the power, 2014-07-30 03:40:57]

Change committed as 286399