test/wcc/data: grow the declarative compiler corpus to 1,224 fixtures

The r-prefixed waves absorb the runtime, reject, and byte-compare rows
of the migrated native carriers; each fixture is one directory with one
case.ww and a //ww:error, //ww:compile, //ww:run, or //ww:run-exit
directive covering both frontends.

test/wcc/data/r71_struct_byval_partial_fit/case.ww

@@ -0,0 +1,11 @@
+//ww:run-exit 48
+package main;
+type pair = struct { a: i64, b: i64 };
+fn manyfn(s0: i64, s1: i64, s2: i64, s3: i64, s4: i64,
+		x: pair) i32 = {
+	return (s0 + s1 + s2 + s3 + s4 + x.a + x.b): i32;
+};
+fn main() i32 = {
+	let p: pair = pair { a = 11i64, b = 22i64 };
+	return manyfn(1i64, 2i64, 3i64, 4i64, 5i64, p);
+};