[Android] Remove global --gc-sections ldflag from Debug targets.

[Android] Remove global --gc-sections ldflag from Debug targets.

After some major cleanup, all but very few Android targets (i.e.
chrome_shell_apk and chrome_unittests_apk) have stopped depending
on the linker GC section to build succesfully.
This change removes the global --gc-section arg from all Debug targets
in order to prevent future regressions.

BUG=159847
TBR=thakis@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=265678

[Primiano Tucci (use gerrit), 2014-04-23 15:30:19]

Nico: TBR-ing this since it is just a one-line cut away from
crrev.com/228003006.
I did remove this line form the original CL because the change was depending on
a WebRTC roll (which was delayed for more than a week) and the remaining gyp
refactoring was getting out of sync.
Now that WebRTC has rolled, we can complete the opera and remove the global
blanket :-)

[Primiano Tucci (use gerrit), 2014-04-23 15:30:26]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2014-04-23 15:30:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/primiano@chromium.org/249513002/1

[Nico, 2014-04-23 16:28:47]

lgtm

[commit-bot: I haz the power, 2014-04-23 17:39:40]

Change committed as 265678