Don't depend on a private libpurple library

libjabber is a private lib so accoriding to Debian policy libjabber should either be public or no be used by chatty:

$ echo 'E: chatty: binary-or-shlib-defines-rpath usr/bin/chatty /usr/lib/purple-2' | lintian-info
E: chatty: binary-or-shlib-defines-rpath usr/bin/chatty /usr/lib/purple-2
N:
N:   The binary or shared library sets RPATH or RUNPATH. This overrides the
N:   normal library search path, possibly interfering with local policy and
N:   causing problems for multilib, among other issues.
N:   
N:   The only time a binary or shared library in a Debian package should
N:   set RPATH or RUNPATH is if it is linked to private shared libraries in
N:   the same package. In that case, place those private shared libraries
N:   in /usr/lib/<package>. Libraries used by binaries in other packages
N:   should be placed in /lib or /usr/lib as appropriate, with a proper
N:   SONAME, in which case RPATH/RUNPATH is unnecessary.
N:   
N:   To fix this problem, look for link lines like:
N:       gcc test.o -o test -Wl,--rpath,/usr/local/lib
N:   or
N:       gcc test.o -o test -R/usr/local/lib
N:   and remove the -Wl,--rpath or -R argument. You can also use the
N:   chrpath utility to remove the RPATH.
N:   
N:   Refer to https://wiki.debian.org/RpathIssue for details.
N:   
N:   Severity: serious, Certainty: possible
N:   
N:   Check: binaries, Type: binary, udeb
N: