Several improvements to abicheck target.  Previous version didn't actually work, probably because we were using relative paths in the generated abi.xml file.  Now we're relying on ACC's ability to diff against a pre-generated ABI "dump" file, so we just have to do a dump  in our "stable" version's directory before running abicheck here.
Several improvements to abicheck target.  Previous version didn't
actually work, probably because we were using relative paths in the
generated abi.xml file.  Now we're relying on ACC's ability to diff
against a pre-generated ABI "dump" file, so we just have to do a dump 
in our "stable" version's directory before running abicheck here.

winsock/mysqlpp,winsock/mysqlpp,winsock/mysqlpp