configure: add hints to a remedy for feature_not_found errors Modify feature_not_found to accept an optional second parameter to be printed after the generic feature not found error. Modify most calls to feature_not_found to provide hints as to the packages that may be missing. The few calls remaining without a remedy are ones I couldn't work out how to remedy myself. Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>