tree-il-src is a vector, replaces tree-il-srcv

* module/language/tree-il.scm (tree-il-src): Always a vector now;
tree-il-srcv is gone.  An incompatible change but we are in the
compiler.
(location): For parse-tree-il, make vector locations instead of alists.
* module/language/tree-il/analyze.scm:
* module/language/tree-il/compile-bytecode.scm:
* module/language/tree-il/compile-cps.scm:
* module/language/tree-il/debug.scm:
* module/language/tree-il/letrectify.scm:
* module/language/tree-il/peval.scm:
* module/system/vm/assembler.scm: Update all uses to expect vectors
instead of alists and to use tree-il-src instead of tree-il-srcv.
* module/language/elisp/compile-tree-il.scm (location): Create vectors,
not alists.
* test-suite/tests/compiler.test ("psyntax"): Update syntax-source
expectation.

module/language/tree-il/debug.scm

@@ -244,7 +244,7 @@
        (visit tail env))
       (_
        (error "unexpected tree-il" exp)))
-    (match (tree-il-srcv exp)
+    (match (tree-il-src exp)
       (#f #t)
       (#((or #f (? string?)) (? exact-integer?) (? exact-integer?)) #t)
       (src (error "bad src" src)))