The abi_check target instroduced as part of WL#4380 verifies
changes to mysql.h. mysql.h in turn includes mysql_version.h.
mysql_version.h is a file that is generated during the configure
phase. We must ensure that mysql_version.h is cleaned only during
distclean and not during clean.

include/Makefile.am:
  This file contains the following changes
  
  1) Moves the cleaning of mysql_version.h from the clean
     phase to the distclean phase.
  
  2) Removes mysql_version.h.in from noinst_HEADERS, this
     entry was reduntant since by virtue of inclusion of
     mysql_version.h mysql_version.h.in is already included.