Assume cross-compilation if host and target os differ

fixes 1674

c_check

@@ -223,7 +223,6 @@ $data =~ /globl\s([_\.]*)(.*)/;
 $need_fu      = $1;
 
 $cross = 0;
-$cross = 1 if ($os ne $hostos);
 
 if ($architecture ne $hostarch) {
     $cross = 1;
@@ -231,6 +230,8 @@ if ($architecture ne $hostarch) {
     $cross = 0 if (($hostarch eq "mips64") && ($architecture eq "mips"));
 }
 
+$cross = 1 if ($os ne $hostos);
+
 $openmp = "" if $ENV{USE_OPENMP} != 1;
 
 $linker_L = "";