[Lazarus] Where is the "maps" unit

[Lubos Pintes]

Hi list,
I tried to compile Lazarus after a long time, to test and possibly close 
issue I reported. Compilation failed with this message:
dbgintfdebuggerbase.pp(39,3) Fatal: Can't find unit maps used by 
DbgIntfDebuggerBase
Fatal: Compilation aborted

I am on Windows 7 64-bit, FPC 2.6.2 which is the stable one if I 
understood properly.
So what is wrong or missing?
Thanks