In C++17, static constexpr members are implicitly inline, so they no
longer require an out-of-line definition.
This patch also removes redundant "const" from the in-class definitions.
Identified with readability-redundant-declaration.
- Put the element size field in the same place for all non-pointer
types.
- Put the element size and address space fields in the same place for
all pointer types.
- Put the number of elements and scalable fields in the same place for
all vector types.
This simplifies initialization and accessor methods isScalable,
getElementCount, getScalarSizeInBits and getAddressSpace.