autogen.sh: use quoted string variables

Place quotes around the $srcdir, $ORIGDIR and $0 variables to prevent
fall-outs, when they contain space.
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

autogen.sh

 #! /bin/sh
 
-srcdir=`dirname $0`
+srcdir=`dirname "$0"`
 test -z "$srcdir" && srcdir=.
 
 ORIGDIR=`pwd`
-cd $srcdir
+cd "$srcdir"
 
 autoreconf -v --install || exit 1
-cd $ORIGDIR || exit $?
+cd "$ORIGDIR" || exit $?
 
 if test -z "$NOCONFIGURE"; then
-    exec $srcdir/configure "$@"
+    exec "$srcdir"/configure "$@"
 fi