build: Add checks for various functions and headers to configure.ac
build: Add checks for various functions and headers to configure.ac

As suggested by `autoscan`.

Pecisk/libgdata,Pecisk/libgdata-gtasks,GNOME/libgdata,Distrotech/libgdata,Pecisk/libgdata-gtasks,Distrotech/libgdata,Distrotech/libgdata,Pecisk/libgdata-gtasks,Pecisk/libgdata,pwithnall/libgdata,pwithnall/libgdata,Pecisk/libgdata