Makefile: move stack-protector availability out of Kconfig

Makefile: move stack-protector availability out of Kconfig

Various portions of the kernel, especially per-architecture pieces,
need to know if the compiler is building with the stack protector.
This was done in the arch/Kconfig with 'select', but this doesn't
allow a way to do auto-detected compiler support. In preparation for
creating an on-if-available default, move the logic for the definition of
CONFIG_CC_STACKPROTECTOR into the Makefile.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>
Tested-by: Laura Abbott <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Josh Triplett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>