This error is not specific to Litespeed but can be encountered while building PHP with MySQL support on 64-bit systems. The fix is to tell the build that the MySQL client is indeed installed, but in a different directory, by adding the following flag to the configure line in Litespeed:
The reason being the build doesn’t know at this point that it is dealing with a 64-bit OS. If adding the above switch does not work, be sure to install the MySQL client and libraries.
That’s all folks!