NetBSD compiler errors concerning HIST_ENTRY

After applying previous patches (MDEV-4553) to 5.5.31 the following also fails to compile:

[ 96%] Building CXX object client/CMakeFiles/mysql.dir/mysql.cc.o
/usr/local/src/mariadb-5.5.31/client/mysql.cc:1057:12: error: 'HIST_ENTRY' does not name a type
/usr/local/src/mariadb-5.5.31/client/mysql.cc: In function 'int not_in_history(const char*)':
/usr/local/src/mariadb-5.5.31/client/mysql.cc:2434:3: error: 'HIST_ENTRY' was not declared in this scope
/usr/local/src/mariadb-5.5.31/client/mysql.cc:2434:15: error: 'oldhist' was not declared in this scope
/usr/local/src/mariadb-5.5.31/client/mysql.cc:2434:51: error: 'history_get' was not declared in this scope

Proposed patch:

92a93,95
> #ifdef HAVE_HIST_ENTRY
> # include <readline/history.h>
> #endif
1049c1052
< extern "C" int add_history(const char command); / From readline directory */
—
> extern "C" void add_history(const char command); / From readline directory */