config: add option to build statically linked toolchain

Add a config option to statically build the host tools.
Impacted tools can use that option to decide wether to build
statically or shared.

For now, no tool uses it, but they'll be added one at a time
in the next commits.

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

 # AVR32 specific configuration file

 config ARCH_avr32

     select ARCH_SUPPORTS_32

     select ARCH_DEFAULT_32

     select ARCH_USE_MMU

     select ARCH_DEFAULT_BE

     select ARCH_SUPPORT_ARCH

     select ARCH_SUPPORT_CPU

     select ARCH_SUPPORT_TUNE

     select ARCH_SUPPORT_FPU

      help

       The AVR32 architecture, as defined by:

         http://www.atmel.com/products/avr32