package/libiscsi: fix build due to warnings

Fixes:
    http://autobuild.buildroot.org/results/55b/55bf50fc7dcd465b71b5757434887dd3d0b25abc/
    http://autobuild.buildroot.org/results/98d/98dcfe5c9fc3babd5c8d3116d5128d437715c44e/

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit d2d81637ee6483aa23a2266154efd3d047bc0bb6)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libiscsi/libiscsi.mk

@@ -11,6 +11,8 @@ LIBISCSI_LICENSE_FILES = COPYING LICENCE-GPL-2.txt LICENCE-LGPL-2.1.txt
 LIBISCSI_INSTALL_STAGING = YES
 LIBISCSI_AUTORECONF = YES
 
+LIBISCSI_CONF_OPTS = --disable-werror
+
 # We need to create the m4 directory to make autoreconf work properly.
 define LIBISCSI_CREATE_M4_DIR
 	mkdir -p $(@D)/m4