Disable stack protector for __libc_preinit

__libc_preinit sets up the stack protector global cookie value, and thus
cannot intialize a stack protector cookie for itself in the function
prologue. LTO compilation can inline functions requiring a stack
protector into __libc_preinit. This patch disables stack protection for
__libc_preinit and forces all potentially inlined functions into a
helper that can have a stack protector.

Test: run bionic-unit-tests

Change-Id: I45911611190f216c91eb6feff722967214c5f99f