Sometime you have to check for different versions of a packages with pkg-config because of new APIs. I had to query the lazyweb and I ended up finding something. Here is the snippet I wrote:

PKG_CHECK_MODULES(GNOMEVFS, [gnome-vfs-2.0 >= 2.14],
  PKG_CHECK_MODULES(GNOMEVFS, [gnome-vfs-2.0 >= 2.12])

Something I haven't seen often is that PKG_CHECK_MODULES allow found and not found action blocks (yes this is in pkg-config main page). The default not found action is to fail. The above code works as follow: check the highest version you need, if not found check the one you can eventually go away with. Define a symbol with a numeric version and pass it to the modules CFLAGS.

Then in the code do:

#if GNOMEVFS_VER >= 214