This makes the host_shared value available to host makefile
fragments.
It uses this to adjust Darwin's mdynamic-no-pic in the case that
shared host resources are required.
Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
config/
* mh-darwin: Require a non-shared host configuration to
enable mdynamic-no-pic where that is supported.