um: Remove copy&paste code from init.h

As we got rid of the __KERNEL__ abuse, we can directly
include linux/compiler.h now.
This also allows gcc 5 to build UML.
Reported-by: Hans-Werner Hilse <hwhilse@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/include/shared/init.h

@@ -40,28 +40,8 @@
 typedef int (*initcall_t)(void);
 typedef void (*exitcall_t)(void);
 
-#ifdef __UM_HOST__
-#ifndef __section
-# define __section(S) __attribute__ ((__section__(#S)))
-#endif
-
-#if __GNUC__ == 3
-
-#if __GNUC_MINOR__ >= 3
-# define __used			__attribute__((__used__))
-#else
-# define __used			__attribute__((__unused__))
-#endif
-
-#else
-#if __GNUC__ == 4
-# define __used			__attribute__((__used__))
-#endif
-#endif
-
-#else
 #include <linux/compiler.h>
-#endif
+
 /* These are for everybody (although not all archs will actually
    discard it in modules) */
 #define __init		__section(.init.text)