All supported hosts now define HAVE_SAFE_SYSCALL, so remove
the ifdefs. This leaves hostdep.h empty, so remove it.
Reviewed-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>