configure: fix version string breakage

As we use the directory names as Makefile targets, they can not contain any
column ':', or else make will complain about 'multiple target patterns'.

Replace the offending ':' with a dash '-', as Titus suggested.

Reported-by: Erdem Budak <erdembudak@hotmail.com>
Reported-by: Titus von Boxberg <titus@v9g.de>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # m68k specific configuration file

 ## depends on EXPERIMENTAL

 ##

 ## select ARCH_SUPPORTS_32

 ## select ARCH_DEFAULT_32

 ## select ARCH_DEFAULT_BE

 ## select ARCH_SUPPORT_CPU

 ##

 ## help The m68k architecture