deb-control(5): fix Multi-Arch description

The field is allowed in “Architecture: all” packages. And “Multi-Arch:
allowed” does not mean that reverse dependencies can be marked as
_needing_ foreign packages but only that they can be marked as _accepting_
foreign packages to satisfy them.

Reported-by: Jakub Wilk <jwilk@debian.org>
Closes: #654453

debian/changelog

@@ -72,6 +72,8 @@ dpkg (1.16.2) UNRELEASED; urgency=low
     to pass an explicit patch file to dpkg-source --commit.
   * Add new --query-features command to dpkg-buildflags. Thanks to Kees Cook
     for the patch. Closes: #651481
+  * Fix description of Multi-Arch in deb-control(5). Closes: #654453
+    Thanks to Jakub Wilk for spotting the mistake.
 
   [ Jonathan Nieder ]
   * Bump po4a version in Build-Depends to 0.41, since earlier versions do

man/deb-control.5

@@ -107,9 +107,8 @@ of a different architecture from itself. The value \fBforeign\fP means that
 the package is not co-installable with itself, but should be allowed to
 satisfy the dependency of a package of a different arch from itself. The
 value \fBallowed\fP allows reverse-dependencies to indicate in their
-Depends field that they need a package from a foreign architecture, but
-has no effect otherwise. This field should not be present in packages
-with the \fBArchitecture: all\fP field.
+Depends field that they accept a package from a foreign architecture, but
+has no effect otherwise.
 .TP
 .BI Source: " source-name"
 The name of the source package that this binary package came from, if