Dpkg::Control::Fields: Put an & before field_capitalize() calls

The definition of the function appears later on, and perl 5.16 gives
warnings about usage before declaration.

Closes: #676262

debian/changelog

@@ -54,6 +54,8 @@ dpkg (1.16.4) UNRELEASED; urgency=low
     a new perl package bumping the perl ABI impossible, as both packages
     become uninstallable. Thanks to Dominic Hargreaves <dom@earth.li>.
     Closes: #675947
+  * Put an & before field_capitalize() calls in Dpkg::Control::Fields to
+    fix a usege before declaration warning with perl 5.16. Closes: #676262
 
   [ Updated man page translations ]
   * German (Helge Kreutzmann).

scripts/Dpkg/Control/Fields.pm

@@ -284,8 +284,8 @@ our %FIELDS = (
     },
 );
 
-my @checksum_fields = map { field_capitalize("Checksums-$_") } checksums_get_list();
-my @sum_fields = map { $_ eq "md5" ? "MD5sum" : field_capitalize($_) }
+my @checksum_fields = map { &field_capitalize("Checksums-$_") } checksums_get_list();
+my @sum_fields = map { $_ eq "md5" ? "MD5sum" : &field_capitalize($_) }
                  checksums_get_list();
 &field_register($_, CTRL_PKG_SRC | CTRL_FILE_CHANGES) foreach @checksum_fields;
 &field_register($_, CTRL_INDEX_PKG) foreach @sum_fields;