extend t/c_cross.t test

needs a arm-linux-gnueabihf-gcc compiler and
a custom /usr/lib/cperl/5.29.1/armv4l-linux/CORE dir though.

t/c_cross.t

@@ -1,20 +1,32 @@
 #! /usr/bin/env perl
 # test -cross=path
-BEGIN {
-  print "1..1\n";
-}
 use strict;
 use Config;
+use Test::More;
+plan tests => 9;
+
+# This should exist for the last test:
+my $crossarch = '/usr/lib/cperl/5.29.1/armv4l-linux/CORE';
 
 sub check_cross {
   my ($file) = @_;
   my $f;
   unless (open($f, "<", $file)) {
-    print "not ok # $file not found\n";
+    ok(0, "$file $!");
     return;
   }
+  # perlpath in config.sh-arm-linux
   while (<$f>) {
-    //;
+    if (m{"", GV_ADD\|GV_NOTQUAL\), "(.+)"\);}) {
+      is ($1, "/usr/bin/perl", "perlpath");
+      next;
+    }
+    if (m{/\* cross \@INC \*/}) {
+      $_ = <$f>;
+      $_ = <$f>;
+      like($_, qr{/armv4l-linux}, 'cross \@INC');
+      next;
+    }
   }
   close $f;
 }
@@ -31,7 +43,7 @@ my $X = $^X =~ m/\s/ ? qq{"$^X" -Iblib/arch -Iblib/lib} : "$^X -Iblib/arch -Ibli
 system "$X -MO=$C,-cross=t/config.sh-arm-linux,-occross.c $pl";
 
 # now grep the result for the right $^X, $^O and @INC
-check_cross('ccross.c');
+check_cross('ccross.c', 1);
 
 system "$X -MO=$C,-O3,-cross=t/config.sh-arm-linux,-occross.c $pl";
 check_cross('ccross.c');
@@ -43,12 +55,15 @@ check_cross('ccross.c');
 system "$X script/perlcc -S --cross=t/config.sh-arm-linux -o ccross $pl";
 check_cross('ccross.c');
 
-if (`which arm-linux-gnueabihf-gcc`) {
-  #require ExtUtils::Embed;
-  my $opts = '-I'.$Config{archlib}.'/CORE';
+if (-d $crossarch and `which arm-linux-gnueabihf-gcc`) {
+  my $opts = "-I$crossarch";
   system("arm-linux-gnueabihf-gcc -c $opts ccross.c");
+} else {
+  ok (1, "skip no arm-linux-gnueabihf-gcc or $crossarch");
 }
 
+unlink $pl;
+
 __DATA__
 require vars;
 vars->import($c);