package/libmodbus: bump to version 3.1.6

Contains a fix for issue discovered post-3.1.5.
See changelog:

https://libmodbus.org/2019/urgent-fix-for-last-releases/

Signed-off-by: Pierre-Jean Texier <pjtexier@koncepto.io>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libmodbus/libmodbus.hash

@@ -1,3 +1,3 @@
 # Locally computed
-sha256  f7a9538f23a8786b1ee62a4b75879b5c0e194e728350de1b741ce7d595970f06  libmodbus-3.1.5.tar.gz
+sha256  d7d9fa94a16edb094e5fdf5d87ae17a0dc3f3e3d687fead81835d9572cf87c16  libmodbus-3.1.6.tar.gz
 sha256  dc626520dcd53a22f727af3ee42c770e56c97a64fe3adb063799d8ab032fe551  COPYING.LESSER

package/libmodbus/libmodbus.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-LIBMODBUS_VERSION = 3.1.5
+LIBMODBUS_VERSION = 3.1.6
 LIBMODBUS_SITE = http://libmodbus.org/releases
 LIBMODBUS_LICENSE = LGPL-2.1+
 LIBMODBUS_LICENSE_FILES = COPYING.LESSER