Fix definition of PAGESIZE and B_PAGE_SIZE

On sparc, the minimal page size we can use is 8K. Since B_PAGE_SIZE and
PAGESIZE defines were hardcoded to 4K, this resulted in a lot of
confusion in all code trying to manipulate pages.

- Remove cpu.h from headers/private/kernel/arch/*. It dates back from
  NewOS and was not used anymore since our kernel uses B_PAGE_SIZE
  (PAGE_SIZE was the only thing defined in this header).
- Add posix/arch/*/limits.h with the arch specific page size and include
  it from the main limits.h.
- Adjust bios_ia32/debug.cpp which was the only place using the
  PAGE_SIZE constant from the deleted headers.
- Change OS.h to define B_PAGE_SIZE to be the same as POSIX PAGESIZE.
- Define PAGESIZE in the build header if the host OS doesn't.

Change-Id: I8c3732cf952ea3c2f088aa16d216678fbf198b96
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3558
Reviewed-by: Adrien Destugues <[email protected]>

headers/os/kernel/OS.h

@@ -7,6 +7,7 @@
 
 /** Kernel specific structures and functions */
 
+#include <limits.h>
 #include <stdarg.h>
 #include <sys/types.h>
 
@@ -21,9 +22,10 @@ extern "C" {
 /* System constants */
 
 #define B_OS_NAME_LENGTH	32
-#define B_PAGE_SIZE			4096
 #define B_INFINITE_TIMEOUT	(9223372036854775807LL)
 
+#define B_PAGE_SIZE			PAGESIZE
+
 enum {
 	B_TIMEOUT						= 0x8,	/* relative timeout */
 	B_RELATIVE_TIMEOUT				= 0x8,	/* fails after a relative timeout