i#1569 AArch64: Handle AArch64 in runsuite_common_pre.cmake.
i#1569 AArch64: Handle AArch64 in runsuite_common_pre.cmake.

On AArch64 we set ARCH_IS_X86 to OFF, and KERNEL_IS_X64 to ON,
and we skip 32-bit builds.

Review-URL: https://codereview.appspot.com/310170043

AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio