Argh, of course it was a bad idea to only rename the directory when the compiler checks the paths recursive. But deleting the directory didn't solve the problem:
Free Pascal Compiler version 2.6.4 [2014/10/11] for arm
Copyright (c) 1993-2014 by Florian Klaempfl and others
Target OS: WinCE for ARM
Compiling alllclunits.pp
Compiling barchart.pp
Compiling lclintf.pas
lclintf.pas(46,28) Fatal: Can not find ShellApi used by LCLIntf, ppu=..\fpc\2.6.4\units\arm-wince\winceunits\shellapi.ppu
I now copied the source files to \fpc\2.6.4\units\arm-wince\winceunits to get it work. This isn't really a big problem, because I use a separte Lazaraus installation just for testing.
Greetings