[gingerBill]

Like with a procedure literal, an asm template now has only its signature checked when it is declared or used.

Its specification block and body are checked later: right after the procedure body it is within, otherwise with the procedure bodies.

• The global dependency graph only walks a template's signature.
• Constants in a body resolve like any identifier, so ones declared later in the block or in a #+lazy file now work.
• A body can name a constant that depends on its own template's signature (e.g. K :: size_of(f(0))).
• A template's @(enable_target_feature) now counts in its body checks. Its callers must enable the same features, as it is inlined, which turns LLVM errors into checker errors.
• On unsupported targets, the signature is checked before the "not supported" error.