Accept VPATH=foo argument in umake.
Accept VPATH=foo argument in umake.

Umake already passes everything of the form a=b to make, but it also
set VPATH on its own, so this must be handled specifically.

	* sdk/umake.in: Handle VPATH= argument on command line.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport