pkg-autotools: remove redundant shell conditional

The libtool patching function checks whether patching libtool is wanted
before doing the actual patching.

This is redundant now, as all callers are now protected by a conditional
block.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Johan Oudinet <johan.oudinet@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>