symb: Remove FB_DATATYPE_BITFIELD and store info on FIELDs directly
symb: Rename symbGetDefaultCallConv() to a more correct name
symb: Clean up unused CASEs in hParamsToStr()
symb: Allow symbGetDefaultParamMode() dtype param to have CONST bits
Remove unused fb_StrAllocTempDescV() code path from rtlStrAllocTmpDesc()
Implement BYVAL AS STRING properly
Copy back string data when passing Z/WSTRINGs to BYREF AS STRING params
symb: Solve out unnecessary variable in symbAddProcResultParam()
symb: Don't specialize some array descriptors to the array's dtype

It was added in 22b784de434ebaf22d75ee8c0bf8dcb114e8d9e8, only for the
C backend, but it doesn't seem to be needed anymore for that.

Anyways, for implementing dynamic array fields, it seems good to avoid
dynamic array descriptors being specialized to the array dtype, because
then we'd need one descriptor for every single dynamic array field. And on
top of that, bydesc parameters already use unspecialized descriptors now,
so extending that to all arrays doesn't seem like a loss. The main
advantage is that we only need to create 1 dynamic array descriptor TYPE
internally, that can be re-used for all dynamic array descriptors.
symb: Re-use the same global type for all dynamic array descriptors