bugfix: the feature test for SSE 4.2 support did not really check if the local CPU indeed has it.

Signed-off-by: Yichun Zhang (agentzh) <agentzh@gmail.com>

util/configure

@@ -632,18 +632,35 @@ _END_
                                          SUFFIX => '.c', TMPDIR => 1,
                                          UNLINK => 1);
 
-            print $out "int main(void) { return 0; }";
+            print $out "
+int main(void) {
+#ifndef __SSE4_2__
+#   error SSE 4.2 not found
+#endif
+    return 0;
+}
+";
             close $out;
 
             my $ofile = tmpnam();
             my $comp = ($cc || 'cc');
+            my $found;
 
             if (system("$comp -o $ofile -msse4.2 -c $cfile") == 0 && -s $ofile) {
-                print "INFO: found -msse4.2 in $comp.\n";
-                $luajit_xcflags .= " -msse4.2";
                 unlink $ofile;
 
-            } else {
+                if (system("$comp -o $ofile -march=native -c $cfile") == 0 && -s $ofile) {
+                    print "INFO: found -msse4.2 in $comp.\n";
+                    $found = 1;
+                    $luajit_xcflags .= " -msse4.2";
+                }
+            }
+
+            if (-f $ofile) {
+                unlink $ofile;
+            }
+
+            if (!$found) {
                 print "WARNING: -msse4.2 not supported in $comp.\n";
             }
         }