Add ILP32 support to gdb.

This patch adds AARCH64:ilp32 support to gdb and sets
up the correct sizes for some types like pointers and long.
Also sets up the correct linker map offsets for Linux.

2016-08-31  Andrew Pinski  <apinski@cavium.com>

	* aarch64-tdep.h (gdbarch_tdep): Add ilp32 field.
	* aarch64-tdep.c (aarch64_gdbarch_init): Setup ILP32 support.
	Make sure the gdbarches have compatible ilp32 flags.
	Set long and ptr sizes correctly for ilp32.
	* aarch64-linux-tdep.c (aarch64_linux_init_abi):
	Add support for ILP32.