This came about because the chunk cache uses ftruncate to cheaply set the file size, and testing failed on the Evergreen variant that explicitly unsets HAVE_FTRUNCATE.

Going over the related conversations in WT-3016 and WT-2336, it seems that we added this not so much because we need to support the ancient Linux versions that don't have it, but because there were some customers with custom filesystems that didn't support it.

Given that this is causing a problem with new code, it's worth asking whether this still something we want to support.