u-a: Include <limits.h> for _POSIX_MAX_PATH

Needed on at least Solaris and Darwin, and as defined per POSIX.

Signed-off-by: Guillem Jover <guillem@debian.org>

debian/changelog

@@ -10,6 +10,7 @@ dpkg (1.15.8.4) UNRELEASED; urgency=low
   * Fix compilation on Solaris and Darwin:
     - Link update-alternatives against libintl if libc does not have i18n
       support.
+    - Include <limits.h> for _POSIX_MAX_PATH in update-alternatives.
     Thanks to Fabian Groffen <grobian@gentoo.org>.
 
   [ Raphaël Hertzog ]

utils/update-alternatives.c

@@ -41,6 +41,7 @@
 #include <assert.h>
 #include <locale.h>
 #include <ctype.h>
+#include <limits.h>
 
 #include <dpkg/macros.h>
 #include <dpkg/i18n.h>