bsd.lib.mk: Prevent "profiling impossible" warning

bsd.lib.mk: Prevent "profiling impossible" warning

The flag combination of "-pg" and "-ffunction-sections" do not mix.
GCC will emit the warning: "-ffunction-sections disabled; it makes
profiling impossible"

This simple modification to bsd.lib.mk will filter out
-ffunction-sections flag whenever it tries to build profile
objects.  The seemingly hundreds of warning in the world build
log are now gone.