Fix by Reuben Thomas on Don's machine. CC optsions passed to GHC now have -optc added at the point where we choose to use GHC as the CC compiler, i.e. at "CC=..." in ghc/rts/Makefile and ghc/compiler/Makefile.
# For an optimised RTS:
GhcRtsHcOpts=-O2
-GhcRtsCcOpts=-O2 -optc-fomit-frame-pointer
+GhcRtsCcOpts=-O2 -fomit-frame-pointer
# Include the front panel code? Needs GTK+.
GhcRtsWithFrontPanel = NO