complibs: remove experimental from versions selection

Since I removed EXPERIMENTAL to most of gcc versions, the configuration
is now broken, as the required companion libraries versions are not
selectable, as they are still hidden behind EXPERIMENTAL.

Reported-by: Claudio Henrique Fortes Felix (chffelix on irc://irc.freenode.net/crosstool-ng)
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 # Compute Blackfin-specific values

 CT_DoArchTupleValues() {

     # The architecture part of the tuple:

     CT_TARGET_ARCH="bfin"

     # gcc ./configure flags

     CT_ARCH_WITH_ARCH=

     CT_ARCH_WITH_ABI=

     CT_ARCH_WITH_CPU=

     CT_ARCH_WITH_TUNE=

     CT_ARCH_WITH_FPU=

     CT_ARCH_WITH_FLOAT=

 }