Issue Description:

The remote mirrors C API currently only supports targets with the same pointer size that remote mirrors itself is running with. It accepts a PointerSize argument, but it just asserts if there's a mismatch. (Older code ignored it entirely.) The underlying C++ code is templated and parameterized with the pointer size, so it should support this. The C code should be modified to use the appropriate template parameter based on the PointerSize argument.