Build nacl-clang target libraries with function-sections
Build nacl-clang target libraries with function-sections

Build target libraries (in particular newlib and libc++) with
-ffunction-sections and -fdata-sections. This makes for slightly larger
libraries and slower links, but allows better GC using --gc-sections, which
is useful for web distributed applications (and the IRT).

R=jvoung@chromium.org
BUG= https://code.google.com/p/nativeclient/issues/detail?id=4088

Review URL: https://codereview.chromium.org/1181823002.

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client