libgo: fix for runtime/check failure with "-O0 -g"

libgo: fix for runtime/check failure with "-O0 -g"

    Tweak the makefile rules for the runtime/check test to
    insure that the runtime package is compiled with
    "-fgo-compiling-runtime". This resolves a test failure
    (unsat on runtime.getcallerpc) when in a build directory where the
    compiler flags have been configured to disable optimization.

    Reviewed-on: https://go-review.googlesource.com/30010

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@240588 138bc75d-0d04-0410-961f-82ee72b054a4