I would like to check this change into the fixincludes directory to
allow me to specify what sed is used by mkheaders. The problem I have
is that I use a build environment when building GCC and that BE includes
a GNU sed (needed when building binutils). mkheaders is saving the
location of that sed and when a user, who doesn't have access to my BE,
tries to run mkheaders to sync the GCC header files with the system
header files it fails because it can't find that sed.
This patch would allow me to tell mkheaders to use the system sed,
which in my case works fine for mkheaders.
I used --with-mkheaders-sed instead of just --with-sed to make it clear
that this only affects what sed mkheaders uses, not what sed the rest of
the GCC build uses.
Tested on IA64 HP-UX, OK for checkin?