Add --disable-shared to --static ./configure option.

To be consistent with --enable-shared alternative to --shared
option.

configure

diff --git a/configure b/configure
index 6d32659..3a8adf0 100755
--- a/configure
+++ b/configure
@@ -140,7 +140,7 @@
     -m* | --mandir) mandir="$2"; shift; shift ;;
     -u* | --uname) uname="$2"; shift; shift ;;
     -s* | --shared | --enable-shared) shared=1; shift ;;
-    -t | --static) shared=0; shift ;;
+    -t | --static | --disable-shared) shared=0; shift ;;
     --solo) solo=1; shift ;;
     --cover) cover=1; shift ;;
     -z* | --zprefix) zprefix=1; shift ;;