mark the old jit tests as unsupported for powerpc64 (for cmake)

mark the old JIT tests as unsupported for powerpc64 - CMake style.
This follows the style used for hexagon/arm64/aarch64.
The equivalent tests still run under the supported MCJIT/*



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211111 91177308-0d34-0410-b5e6-96231b3b80d8