Blender Git Loki

makesdna: fix parsing 'const', 'struct', 'unsigned' as a prefix

DNA parsing assumed any identifier which starts with
(`struct`, `unsigned`, `const`) was that identifier.

So a struct called `constTest foo;` would be parsed as `est foo;`.

Add utility function to check identifiers are not
part of a larger identifier.

This also supports skipping these identifiers in any order.

Reviewed By: LazyDodo

Ref D11837