sparseirq: move __weak symbols into separate compilation unit

GCC has a bug with __weak alias functions: if the functions are in
the same compilation unit as their call site, GCC can decide to
inline them - and thus rob the linker of the opportunity to override
the weak alias with the real thing.

So move all the IRQ handling related __weak symbols to kernel/irq/chip.c.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

init/main.c

@@ -539,16 +539,6 @@ void __init __weak thread_info_cache_init(void)
 {
 }
 
-int __init __weak arch_early_irq_init(void)
-{
-	return 0;
-}
-
-int __init __weak early_irq_init(void)
-{
-	return arch_early_irq_init();
-}
-
 asmlinkage void __init start_kernel(void)
 {
 	char * command_line;