cc/gcc: pass the companion libs prefix to cc_core

In case of canadian-cross, the companion libraries are not the same for
the core cc (they run on 'build') as they are for the final cc (they run
on 'host').

Prepare for this differentiation (coming later), while retaining the
current behavior (to use the same compblibs).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # Super-H specific configuration file

 ## select ARCH_SUPPORTS_32

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_SUPPORTS_BOTH_ENDIAN

 ## select ARCH_DEFAULT_LE

 ##

 ## help The Super-H architecture, as defined by:

 ## help     http://www.renesas.com/fmwk.jsp?cnt=superh_family_landing.jsp&fp=/products/mpumcu/superh_family/