[syslog-ng] stale submodules for ivykis and libmongo-client in 3.5.x

[Nix]

spindle 1469 /usr/src/syslog-ng/syslog-ng% git submodule update
fatal: reference is not a tree: ec9066dcc66b33e3767b4729f86844549f004657
fatal: reference is not a tree: cf44084c01a4228244f0dc079c43f94f67462537
Unable to checkout 'ec9066dcc66b33e3767b4729f86844549f004657' in submodule path 'lib/ivykis'
Unable to checkout 'cf44084c01a4228244f0dc079c43f94f67462537' in submodule path 'modules/afmongodb/libmongo-client'

That this has been true for a month makes me wonder how many people are
actually building syslog-ng from git...

-- 
NULL && (void)