A few fixes for 32-bit compiles

- Change the HAVE_SSE to HAVE_SSE4_2 and only provide it on
  x86-64.
- Cast two values that otherwise cause the compiler to warn on 32-bit

Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/arch/arch-x86_64.h b/arch/arch-x86_64.h
index 3ea8070..6dbeee0 100644
--- a/arch/arch-x86_64.h
+++ b/arch/arch-x86_64.h
@@ -48,7 +48,7 @@
 }
 
 #define ARCH_HAVE_FFZ
-#define ARCH_HAVE_SSE
+#define ARCH_HAVE_SSE4_2
 #define ARCH_HAVE_CPU_CLOCK
 
 #endif