Hello David,
Well, I don't know why, but yesterday I only checked the gmp-devel, which was already installed. With your reply now I also checked the mpfr-devel, which wasn't installed yet 
Here we say: Thinking is an issue of luck... and luck isn't an everyday-issue
Now it is installed, and the configure-command now terminates without error-message. And so there is really a lot of time for a lot of coffee
OK, everything went fine. Make and make install as well. The version-check says gcc-4.3.4.
ls -la /dev/ttyUSB0 shows
crw-rw---- 1 root dialout 188, 0 Mar 3 10:31 /dev/ttyUSB0, -> OK
The user is member of the dialout- and the uucp-group. -> OK
The librxtx.so and the RXTXcomm.jar are the original-versions, as part of the original arduino-0018-installation. --> OK
I connect the cable to my boardie -->, green LED, Pin13LED already blinking --> OK
I can start the arduino-IDE with only the old warning of the version-missmatch of the rxtx-library (what we are expecting --> OK)
The Serial-port is shown in normal state (can be selected or unselected) --> OK
A test-sketch can be opened (choosing the simple blinker) --> OK
Trying to upload the programm to the board --> NOT OK
Protocol:
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c: In function 'attachInterrupt':
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:91: error: 'EIMSK' undeclared (first use in this function)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:91: error: (Each undeclared identifier is reported only once
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:91: error: for each function it appears in.)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:91: error: 'INT0' undeclared (first use in this function)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:95: error: 'INT1' undeclared (first use in this function)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c: In function 'detachInterrupt':
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:135: error: 'EIMSK' undeclared (first use in this function)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:135: error: 'INT0' undeclared (first use in this function)
/home/rafa/bin/arduino-IDE/arduino-0018/hardware/arduino/cores/arduino/WInterrupts.c:138: error: 'INT1' undeclared (first use in this function)
Buhuhuhu... It could have been such a wonderful day... buhuhuhuuuuuuuuuuuuu.... but arduino does not like me ....buhuhuhuhuhhhuuuu
I guess I have to drink the whole virtual box of beer on my own... 
... right now... buhuhuhuhuuuuuuuuuuuuuuuuuuu !!!!!!!!!
Whats going on there ?
More Ideas ?
Thanks, hicks... Rafa