m68k: Make gcc aware that BUG() does not return

Use `__builtin_trap()' instead of `asm volatile("illegal")' in the m68k BUG()
macros (as suggested by Andrew Pinski), to kill warnings in code that assumes
BUG() does not return.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/asm-m68k/bug.h

@@ -7,7 +7,7 @@
 #ifndef CONFIG_SUN3
 #define BUG() do { \
 	printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); \
-	asm volatile("illegal"); \
+	__builtin_trap(); \
 } while (0)
 #else
 #define BUG() do { \
@@ -17,7 +17,7 @@
 #endif
 #else
 #define BUG() do { \
-	asm volatile("illegal"); \
+	__builtin_trap(); \
 } while (0)
 #endif