Fix memory map: malloc overwriting symtab/stabs.

	The symbol table and source line table are loaded at the 1Mb mark,
	which coincides with an entry in the BIOS memory map, which is
	used by malloc.

	The debug_load_symboltable method now updates the memory map,
	which fixes the weird source line printouts in ps and the interrupt
	handler.

kernel/debugger.s:
	call ramdisk_load_image in all cases and have it update the memory map.

kernel/mem.s:
	when looping through the memory map, check the BIOS type field for 0,
	not the ACPI field. Also print the ACPI field value.

	add print_memory_map - used while debugging the memory-map update code.

kernel/realmode.s:
	Define a constant to indicate the max size of the memory map.
	Increase the memory map to 20 entries (biggest seen is VMWare with 10).