kexec, x86: Need a new e820 type support for kexec

[Toshi Kani]

Hello,

ACPI 6.0 defines a new type in e820, AddressRangePersistentMemory (7), for
NVDIMM.  On a system with NVDIMM, kexec displays the following error
message and sets it to RANGE_RESERVED as the fallback type.

Unknown type (Persistent Memory) while parsing
/sys/firmware/memmap/34/type. Please report this as bug. Using
RANGE_RESERVED now.

This new type is defined in "arch/x86/include/uapi/asm/e820.h" in 4.2-rc1
as follows. 

  #define E820_PMEM       7

kexec needs to know this new type, but I think its build env includes
"/usr/include/asm/e820.h", which is provided by a distribution.  On Fedora
22, kernel-headers-4.0.6-300.fc22.x86_64 is the latest kernel header
package and it will take a while for 4.2 headers.

How do we handle such kernel header dependency in the kexec build env?

Thanks,
-Toshi