Update to xtrs-4.9d, with lots of bug fixes and improvements.
slipped through the cracks. neeed for 4.9nb5 and later.
Fix PR pkg/47425.
ftp.NetBSD.org and its mirrors has wrong tar ball.
Fix PR pkg/47425.
Oops. PKGNAME_NOREV is not suitable, use DISTNAME instead.
xtrs -> 4.9d
Detect arm MACHINE_ARCH, and set --cpu accordingly, so it can build
on NetBSD ARM platforms.  Tested on my Sheevaplug.

XXX will probably need similar treatment for mips and sh3.