Linux build: Use sysroot when calculating dependencies

third_party/dpkg-dev/scripts/Dpkg.pm

+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package Dpkg;
+
+use strict;
+use warnings;
+
+our $VERSION = '1.01';
+
+use Exporter qw(import);
+our @EXPORT_OK = qw($PROGNAME $PROGVERSION $CONFDIR $ADMINDIR $LIBDIR $DATADIR);
+our @EXPORT = qw($version $progname $admindir $dpkglibdir $pkgdatadir);
+
+our ($PROGNAME) = $0 =~ m{(?:.*/)?([^/]*)};
+
+# The following lines are automatically fixed at install time
+our $PROGVERSION = '1.17.x';
+our $CONFDIR = '/etc/dpkg';
+our $ADMINDIR = '/var/lib/dpkg';
+our $LIBDIR = '.';
+our $DATADIR = '..';
+$DATADIR = $ENV{DPKG_DATADIR} if defined $ENV{DPKG_DATADIR};
+
+# XXX: Backwards compatibility, to be removed on VERSION 2.00.
+## no critic (Variables::ProhibitPackageVars)
+our $version = $PROGVERSION;
+our $admindir = $ADMINDIR;
+our $dpkglibdir = $LIBDIR;
+our $pkgdatadir = $DATADIR;
+## use critic
+
+1;