[mdb-dev] don't compile if no readline.h

[Christian L. <chr...@la...>]

Hello,
  I use mdbtools 0.5 for a personal project since last week.
  I just downloaded 0.6pre version, and "make" failed.
  "configure" correctly found that readline.h is not installed, but
mdb-sql.c doesn't nest "*_history" function calls with
"ifdef HAVE_READLINE".

  Here is a patch to apply to mdb-sql.c file to add these ifdef

  Hope this helps,

Bye, Pif.