flang2 calls the function make_load() to create various types of load
instructions in the LLVM IR output. The function accepts a "flags" argument
of type LL_InstrListFlags which should encode the alignment of the load,
among other things. Apparently, for the IL_LDSCMPLX, IL_LDDCMPLX, and
IL_LDQCMPLX opcodes, the flags had never been computed correctly. This
patch makes such loads consistent with loads of other types, and also adds
a test case.