sh: switch to saved_sigmask-based sigsuspend()/rt_sigsuspend()

Complete the move of sh64 to it, trim the crap from prototypes,
tidy up a bit.  Infrastructure in do_signal() had already been
there, in signal_64 as well as in signal_32 (where it was already
used).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/sh/include/asm/unistd.h b/arch/sh/include/asm/unistd.h
index a42a561..e800a38 100644
--- a/arch/sh/include/asm/unistd.h
+++ b/arch/sh/include/asm/unistd.h
@@ -1,13 +1,11 @@
 #ifdef __KERNEL__
 # ifdef CONFIG_SUPERH32
-
 #  include "unistd_32.h"
-#  define __ARCH_WANT_SYS_RT_SIGSUSPEND
-
 # else
 #  include "unistd_64.h"
 # endif
 
+# define __ARCH_WANT_SYS_RT_SIGSUSPEND
 # define __ARCH_WANT_IPC_PARSE_VERSION
 # define __ARCH_WANT_OLD_READDIR
 # define __ARCH_WANT_OLD_STAT