perl: Use absolute paths for opening database

This makes distcheck happy which runs the build in a different
directory from the source directory.
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

Makefile.am

@@ -160,7 +160,7 @@ build-perl:
 
 .PHONY: check-perl
 check-perl:
-	cd $(builddir)/src/perl && $(MAKE) test
+	cd $(builddir)/src/perl && $(MAKE) test srcdir=$(abs_srcdir)
 
 .PHONY: install-perl
 install-perl:

src/perl/t/Location.t

@@ -9,7 +9,7 @@ use strict;
 use warnings;
 
 # Where to find the test database.
-my $testdb = "../../testdata/test.db";
+my $testdb = "$ENV{'srcdir'}/testdata/test.db";
 
 use Test::More tests => 5;
 BEGIN { use_ok('Location') };