[Lazarus] Make bigide fail with FPC 2.6.4 RC1

[Gabor Boros]

Hi,

I tried to compile fixes_1_2(43803) and trunk(43819) with 2.6.4 RC1 on 
Win32 without success. Error message is same: "registersqldb.pas(91,5) 
Fatal: Can't find unit mysql56conn used by registersqldb".

Gabor