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>

 # ia64 specific config options

 # depends on EXPERIMENTAL

 config ARCH_ia64

     select ARCH_SUPPORTS_64

     select ARCH_DEFAULT_64

     select ARCH_USE_MMU

     select ARCH_SUPPORTS_BOTH_ENDIAN

     help

       The ia64 architecture, as defined by:

         http://www.intel.com/design/itanium/arch_spec.htm