pidgin/pidgin

Fix a bug where we tell the preferences to disconnect the wrong signals

Testing Done:
Compiled and ran, didn't seen any issues, but then again we didn't see issues before either, but this was clearly wrong.

Reviewed at https://reviews.imfreedom.org/r/184/
subdir('libpurple')
subdir('protocols')
if ENABLE_GTK
subdir('pidgin')
endif
if enable_consoleui
subdir('finch')
endif