- have geany 1.33 installed
 - you want to use geany pluings for the same version
 - you have downloaded and unpacked source distribution
 - you get an error while running ./configure under slackware64 14.2 similar linux flavor
 
find /usr |grep "geany.pc"
take note where the "geany.pc" is located and append to PKG_CONFIG_PATH
ie if the file is located under /usr/local/lib/pkgconfig
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
then you can run ./configure again without errors