I've been carrying around the following patch for some time. I noticed
that both i386-sol2-nat.c and i386-v4-nat.c are Solaris-only now and it
seems confusing to carry both around.
So this patch merges i386-v4-nat.c into i386-sol2-nat.c, simplifying it
in a couple of places, like removing checks for macros that are always
defined.
Tested on 64-bit Solaris 11.5/x86 (amd64-pc-solaris2.11) and 32-bit
Solaris 11.3/x86 (i386-pc-solaris2.11) half a year ago.