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/r76_infer_struct_big_sret_ptr/case.ww

@@ -0,0 +1,6 @@
+//ww:run-exit 10
+package main;
+type big = struct { a: i64, b: i64, c: i64, d: i64 };
+fn make(flag: i32) big = { if (flag == 0) { return big { a = 1i64, b = 2i64, c = 3i64, d = 4i64 }; }; return big { a = 10i64, b = 20i64, c = 30i64, d = 40i64 }; };
+fn use_(p: *big, which: i32) i32 = { if (which == 0) { return (p.a + p.b + p.c + p.d): i32; }; return (p.a * p.b * p.c * p.d): i32; };
+fn main() i32 = { let p = make(0); return use_(&p, 0); };