Fix Coverity issue 1212355

Coverity had informed us that a variable could be null at the point where it
was being dereferenced during code generation.  This inserts a minor check to
make sure that is not the case.  Tested over release/examples and extern/ferguson
with --llvm, as the surrounding code was referencing llvm concepts.
Given that the attempt to evaluate NULL->symbol is very likely to generate a segfault, we can reasonably conclude that baseType is reliably non-NULL.  It may be that baseType->symbol->hasFlag(FLAG_WIDE_CLASS) guarantees that base.isLVPtr == GEN_WIDE_PTR.  Putting the assertion:
INT_ASSERT(!baseType || !baseType->symbol->hasFlag(FLAG_WIDE_CLASS) || base.isLVPtr==GEN_WIDE_PTR)
before the "if" would verify this assumption.