sh: Terminate .eh_frame in VDSO with a 4-byte 0.

It's assumed that .eh_frame is terminated with 4-byte 0 in shared
libraries and executable.  It seems to be the case for VDSOs too.
Without this terminator, I saw failures when unwinding from VDSO,
though I don't know how other architectures handle this issue.
For the normal libs, crtendS.o gives this terminator.  We can use
such terminating objects.  Or we can add a 4-byte 0 with modifying
the linker script like as the patch below.
Signed-off-by: Kaz Kojima <kkojima@rr.iij4u.or.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/vsyscall/vsyscall.lds.S

@@ -38,7 +38,10 @@ SECTIONS
 	.text		: { *(.text) } 			:text	=0x90909090
 	.note		: { *(.note.*) }		:text	:note
 	.eh_frame_hdr	: { *(.eh_frame_hdr ) }		:text	:eh_frame_hdr
-	.eh_frame	: { KEEP (*(.eh_frame)) }	:text
+	.eh_frame	: {
+		KEEP (*(.eh_frame))
+		LONG (0)
+	}						:text
 	.dynamic	: { *(.dynamic) }		:text	:dynamic
 	.useless	: {
 	      *(.got.plt) *(.got)