fix `durep -hs 1g` output

Patch by Stephen Tallowitz

http://bugs.gentoo.org/108942

--- durep
+++ durep
@@ -468,7 +468,7 @@
     elsif ($temp =~ m/^[mM]/) {
       return $size * 1048576;
     }
-    elsif ($temp =~ m/^[mM]/) {
+    elsif ($temp =~ m/^[gG]/) {
       return $size * 1048576 * 1024;
     }
     return $size;