Makefile: adding config variable for Os/O2/O3 compilation

Conflicts:

	init/Kconfig
Makefile: Added Snapdragon optimizations
kernel/sysctl: fix: 'warning: 'kbuf' may be used uninitialized in this function'

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
kernel/sysctl: fix: 'warning: 'kbuf' may be used uninitialized in this function' #2

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>
kernel/Makefile: Don't use highest optimization level on workqueue.c

Conflicts:

	kernel/Makefile
kernel: cgroup: fix warning: 'it.task' may be used uninitialized