acinclude.m4:
New macro rule for ha_blackhole.
configure.in:
Rule enabling blackhole engine
sql/Makefile.am:
Additions to Makefile for blackhole engine
sql/handler.cc:
Ifdef enable code for blackhole (and message for "what does this thing do").
sql/handler.h:
Flag for storage engine type.
sql/mysql_priv.h:
Added blackhole type.
sql/mysqld.cc:
Updates for building backhole.
sql/set_var.cc:
Show variable for blackhole engine