fix EUMM 7.04_01 which comes with Perl 5.22.0

with static lib build, we cannot call _find_magic_vstring(),
which does a `require B;` and B is not a pure Perl module.

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>

--- a/cpan/ExtUtils-MakeMaker/lib/ExtUtils/MakeMaker/version/vpp.pm
+++ b/cpan/ExtUtils-MakeMaker/lib/ExtUtils/MakeMaker/version/vpp.pm
@@ -933,7 +933,7 @@ sub _un_vstring {
     if ( length($value) >= 3 && $value !~ /[._]/
 	&& _is_non_alphanumeric($value)) {
 	my $tvalue;
-	if ( $] ge 5.008_001 ) {
+	if ( $Config{usedl} && ( $] ge 5.008_001 ) ) {
 	    $tvalue = _find_magic_vstring($value);
 	    $value = $tvalue if length $tvalue;
 	}