Remove SAFECFLAGS. It was a workaround for failures in old awk script

Remove SAFECFLAGS.  It was a workaround for failures in old awk script
used to generate the crti.S and crtn.S files.  Since we don't use that
anymore, keeping the workaround makes no sense.

Furthermore, in most cases, SAFECFLAGS was not picking up all the
needed flags, causing crti.o and crtn.o to not be built PIC.
Which is very bad.  Removing SAFECFLAGS and using CFLAGS fixes
that as well.