Building 5.1-RELEASE on 4.8

[John Morgan Salomon]

Hi there,

has anyone successfully managed to compile 5.1-RELEASE
from cvsup?

I have a much-played-with 4.8 system, on which I've repeatedly
tried to compile 5.1-RELEASE.  I have a new 4.8-RELEASE build
from cvsup on the machine;  when trying to build 5.1-RELEASE,
I inevitably get a wide variety of errors from include files. 

I've cleaned out /usr/obj before starting;  the errors are
too numerous to all list, but here's a few:

/usr/include/machine/_types.h:45: redefinition of `__int8_t'
/usr/include/machine/ansi.h:130: `__int8_t' previously declared here

/usr/include/sys/_sigset.h:55: redefinition of `struct __sigset'
In file included from /usr/include/sys/signal.h:178,
                 from /usr/include/sys/param.h:98,
                 from /usr/src-5.1/src/usr.bin/make/arch.c:95:
/usr/include/machine/signal.h:130: syntax error before `__aligned'

/usr/include/sys/_sigset.h:55: redefinition of `struct __sigset'
In file included from /usr/include/sys/signal.h:178,
                 from /usr/include/sys/param.h:98,
                 from /usr/src-5.1/src/usr.bin/make/arch.c:95:

I know according to UPGRADE.TXT binary upgrades are not possible,
but I also have not managed to build a 5.1 sysinstall to just install
from a filesystem.  Does anyone have any tips/tricks for me?  Unfortunately
this laptop has no external boot media (floppy/cdrom/etc) so I can't just
install it afresh.

Cheers,

-John