pidgin/pidgin

Remove the log reader plugin now that the History API has landed.

At some point we can come back and integrate this code into purple-history but
right now it's just dead weight.

Testing Done:
Compiled and ran and verified there were no issues.

Reviewed at https://reviews.imfreedom.org/r/1036/
if ENABLE_DOC
subdir('reference')
endif
if ENABLE_GTK
pidgin_man = configure_file(
input : 'pidgin3.1.in',
output : 'pidgin3.1',
configuration : man_conf,
install : true,
install_dir : get_option('mandir') / 'man1')
endif
if enable_consoleui
finch_man = configure_file(
input : 'finch3.1.in',
output : 'finch3.1',
configuration : man_conf,
install : true,
install_dir : get_option('mandir') / 'man1')
endif