[ndk][conf] Shrink binary sizes when cross-compiling.

[1bb7be30] WenHan Gu <Wenhan.gu@mediatek.com>
Shrink binary sizes when cross-compiling.

[6230037c] Ray Donnelly <mingw.android@gmail.com>
Fixes for "Shrink binary sizes when cross-compiling."

[43153c92] Ray Donnelly <mingw.android@gmail.com>
Fix config comment about -Wl,--gc-sections.

Cherry-picked and squashed from release_33 branch.
Regenerated with ./autoconf/AutoRegen.sh.

Change-Id: I7085a24bbee9cbc78fd977cee853c8da37346524