Fix multiple defined symbol errors

Use of __inline__ by projects in bootable/* was causing problems with
clang. Following the BKM and replaced use of __inline__ with
__attribute((__gnu_inline)).

Change-Id: If4ccfded685bb2c9d9c23c9b92ee052208399ef0
Author: Edwin Vane <edwin.vane@intel.com>
Reviewed-by: Kevin P Schoedel <kevin.p.schoedel@intel.com>