lguest: use bool instead of int

Impact: clean up

Rusty told me, some time ago, that he had become a fan of "bool".
So, here are some replacements.

Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

drivers/lguest/core.c

@@ -152,8 +152,8 @@ static void unmap_switcher(void)
  * code.  We have to check that the range is below the pfn_limit the Launcher
  * gave us.  We have to make sure that addr + len doesn't give us a false
  * positive by overflowing, too. */
-int lguest_address_ok(const struct lguest *lg,
-		      unsigned long addr, unsigned long len)
+bool lguest_address_ok(const struct lguest *lg,
+		       unsigned long addr, unsigned long len)
 {
 	return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
 }