Reduce the number of global variables

Reduce the number of global variables

In preparation for strictly limiting the list of variables that are
exported (global) in the core, delete any unused variables, rewrite
variable declarations in C that are not referenced by asm and delete
files that are no longer included in other asm files.

Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>