toolchain_build: Fiddle libgcc and glibc builds closer to final form
toolchain_build: Fiddle libgcc and glibc builds closer to final form

This updates the gcc and glibc revisions to bring in GCC driver and
libgcc changes, and to bring in the current glibc ToT.  The build
rules are tweaked slightly to handle the libgcc changes and to
remove the temporary -Wl,-Ttext-segment=... kludge that is now
handled in the GCC driver.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3068
TEST= toolchain trybots
R=dschuff@chromium.org

Review URL: https://codereview.chromium.org/1112273002

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