cc/gcc: build bare-metal gcc statically

- add a new parameter to do_cc_core: build_statically=[yes|no]
- pass build_statically=yes in core_pass_2 when doing bare_metal
- fix handling the static / static libstdc++ / static complibs stuff
- add a commment to keep both blocks (in core and final) in sync

Signed-off-by: "Bryan Hundven" <bryanhundven@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # powerpc specific configuration file

 config ARCH_powerpc

     select ARCH_SUPPORTS_32

     select ARCH_SUPPORTS_64 if EXPERIMENTAL

     select ARCH_DEFAULT_32

     select ARCH_USE_MMU

     select ARCH_SUPPORT_ABI

     select ARCH_SUPPORT_CPU

     select ARCH_SUPPORT_TUNE

     help

       The PowerPC architecture, as defined by:

         http://www.ibm.com/developerworks/eserver/articles/archguide.html