Log Message:
libusb-compat: Update to 0.1.7.

There are no meaningful changes in this release compared to 0.1.6rc2, it
is primarily a tag update.  However, adding gsed to USE_TOOLS fixes an
issue where the output of ldd was not parsed correctly by either illumos
sed or nbsed, resulting in dlopen failures for libusb-0.1.so.

Fixes joyent/pkgsrc#117.