Revises microkernel initialization code by incorporating the existing
_k_kernel_init() and main() routines into _main(). This optimizes kernel
initialization a bit, and allows application code to use main()
if desired -- for example, as the entry point to an application task.
The change also eliminates the need for sysgen to generate a routine
whose content is always the same.
This change preserves the existing order of operations done during
kernel initialization, and leaves further improvements for later.
Change-Id: Ie03d8a6f38f8a311f398667ed977fd8478719d70
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>