[ARM-softfp/Linux] Get precise type for pointer-size struct

[ARM-softfp/Linux] Get precise type for pointer-size struct

Compiler::getPrimitiveTypeForStruct may return TYP_FLOAT but is off on softfp.
So we need to check that in another way rather than `IsHfa()`.
Otherwise struct types with single float32 will make inconsistency in gentree.
Which ends up with assert failure "Bad IL: Illegal assignment of float into integer!".

Check is done in Compiler::getPrimitiveTypeForStruct, by isSingleFloat32Struct.

Fix #6051