ltrace: 7.2 -> 7.3

Upgrade ltrace from 7.2 to 7.3.

* update SRC_URI and SRCREV
* drop backport patch 0001-In-Linux-backend-initialize-linkmap-struct.patch
* fix error when compile with gcc 5.2

Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>