[ndk][conf] Add an option --enable-shrink-binary-size to configure.

This option could reduce the LLVM tools by "-fdata-sections,
-ffunction-sections" and "--gc-sections". Note that with
--enable-shrink-binary-size, your LLVM tools might not be
able to load plugins (ex: LLVMPolly.so).

The default is off to make NDK llvm tools support plugin.

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

Change-Id: Ie4c729728349e038af81d68e47989d84fb760880

Conflicts:
  configure