Switch arm libcorkscrew over to <sys/ucontext.h>.

#include <elf.h>

#include <cutils/log.h>

#if !defined(__BIONIC_HAVE_UCONTEXT_T)

/* Old versions of the Android <signal.h> didn't define ucontext_t. */

#include <asm/sigcontext.h> /* Ensure 'struct sigcontext' is defined. */

/* Machine context at the time a signal was raised. */

typedef struct ucontext {

    uint32_t uc_flags;

    struct ucontext* uc_link;

    stack_t uc_stack;

    struct sigcontext uc_mcontext;

    uint32_t uc_sigmask;

} ucontext_t;

#endif /* !__BIONIC_HAVE_UCONTEXT_T */

#include <ucontext.h>

/* Unwind state. */

typedef struct {