Add support for arm64-linux (#1)

Add support for arm64-linux

Copied the latest config.guess
Copied the latest linux_syscall_support.h from google LSS repository with aarch64 support Merged some changes from existing coredumper linux_syscall_support.h that are required but absent in the latest LSS.
Added preprocessor conditions for aarch64
Copied the GP and FP registers structures from glibc.
Defined FRAME and SET_FRAME macros FRAME is defined via getcontext() function. It is simpler than using asm.
In CreateElfCore() skip [vvar] memory segment. A process fails to read this segment. On x86_64 [vvar] is disabled for core dump, but on ARM64 it is not. It is the only segment that is marked as "pure PFN range" on the both architectures.
Make stack pointer 16-byte aligned in local_clone() on all architectures.
Add a separate ifdef section to read registers using PTRACE_GETREGSET. PTRACE_GETREGS and PTRACE_GETFPREGS are not supported on arm64-linux

madscientist / google-coredumper