[bug-diffutils] Portability fixlets for MSVC

[Peter Rosin]

Hi!

For thrills I tried to build diffutils in MSYS with the following
configure line:

.../configure \
CC="cl -nologo" \
CFLAGS=-MD \
AR="/path/to/recent/automake/lib/ar-lib lib" \
STRIP=: \
RANLIB=:

I don't know if you (or anyone) cares about building diffutils with
MSVC, but I found a few trivial things to make that complete w/o
error and is thus sending some patches.

Cheers,
Peter

[PATCH 1/3] build: use additional modules needed by MSVC
[PATCH 2/3] portability: declare variables first in blocks
[PATCH 3/3] portability: use raise(2) instead of kill(2)