Don't use -fomit-frame-pointer for ipl_funcs.c if ${PROF} is nonempty,
is incompatible with -pg. (We use a different version of mcount for
profiling frame-pointer-less assembler functions, but gcc doesn't know
about this.)

Added a missing dependency.

Cleaned up trailing backslashes.

Added comment about config's limitations/bugs handling dependencies and
backslashe/newlines.

Finished removing support for isdn drivers.