Build the Apple-style stage2 with full debug info

Green dragon had a green stage2 modules bot for a long time now[1] and
it is time to retire it and make a modules build the default for
Apple-style stage2 builds.

This patch switches the debug info generation from -gline-tables-only
to -g since full debug info does no longer cause any memory issues
even for full LTO builds [2].

[1] http://green.lab.llvm.org/green/job/clang-stage2-cmake-modulesRDA_build/
[2] http://llvm.org/devmtg/2015-10/#talk19
rdar://problem/28672159

llvm-svn: 302685