autogen.sh: pass --force to autoreconf, quote string variables

By passing --force autoreconf will update all the aux files, which would
otherwise be ignored if one updates autoconf/automake.

Quote the $srcdir, $ORIGDIR and $0 variables to prevent fall-outs, when
it contains space.

v2: Also handle $srcdir and $0.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
diff --git a/autogen.sh b/autogen.sh
index fc34bd5..81e182d 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -6,8 +6,8 @@
 ORIGDIR=`pwd`
 cd $srcdir
 
-autoreconf -v --install || exit 1
-cd $ORIGDIR || exit $?
+autoreconf --force --verbose --install || exit 1
+cd "$ORIGDIR" || exit $?
 
 if test -z "$NOCONFIGURE"; then
     $srcdir/configure "$@"