SMP - Cpu local variables

- most global variables carry information which is specific to the
  local CPU and each CPU must have its own copy

- cpu local variable must be declared in cpulocal.h between
  DECLARE_CPULOCAL_START and DECLARE_CPULOCAL_END markers using
  DECLARE_CPULOCAL macro

- to access the cpu local data the provided macros must be used

	get_cpu_var(cpu, name)
	get_cpu_var_ptr(cpu, name)

	get_cpulocal_var(name)
	get_cpulocal_var_ptr(name)

- using this macros makes future changes in the implementation
  possible

- switching to ELF will make the declaration of cpu local data much
  simpler, e.g.

  CPULOCAL int blah;

  anywhere in the kernel source code

kernel/kernel.h

@@ -2,7 +2,9 @@
 #define KERNEL_H
 
 /* APIC is turned on by default */
+#ifndef CONFIG_APIC
 #define CONFIG_APIC
+#endif
 /* boot verbose */
 #define CONFIG_BOOT_VERBOSE
 /*
@@ -52,6 +54,7 @@
 #include "profile.h"		/* system profiling */
 #include "perf.h"		/* performance-related definitions */
 #include "debug.h"		/* debugging, MUST be last kernel header */
+#include "cpulocals.h"
 
 #endif /* __ASSEMBLY__ */