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/r778_stream_read_unread/case.ww

@@ -0,0 +1,30 @@
+//ww:run-exit 47
+// Migrated from 778_bufio_vstream_run row stream_read_unread.
+package main;
+import os;
+import bufio;
+import memio;
+import io;
+export fn main() i32 = {
+    let raw: [8]u8;
+    raw[0] = 65u8; raw[1] = 66u8; raw[2] = 67u8; raw[3] = 68u8;
+    raw[4] = 69u8; raw[5] = 70u8; raw[6] = 71u8; raw[7] = 72u8;
+    let mst: memio.stream = memio.fixed(raw[0:8]);
+    let msrc: io.stream = &mst.vt;
+    let rbuf: [8]u8;
+    let wbuf: [4]u8;
+    let b: bufio.stream = bufio.init(msrc, rbuf[0:8], wbuf[0:4]);
+    let vs: io.stream = &b.vt;
+    let out: [4]u8;
+    let rd1 = io.read(vs, out[0:3]);
+    let n1: size = 0;
+    if (rd1 is size) { n1 = rd1 as size; };
+    if (n1 != 3: size) { return 91; };
+    if (out[0] != 65u8 || out[2] != 67u8) { return 92; };
+    let rd2 = io.read(vs, out[0:4]);
+    let n2: size = 0;
+    if (rd2 is size) { n2 = rd2 as size; };
+    if (n2 != 4: size) { return 93; };
+    if (out[0] != 68u8 || out[3] != 71u8) { return 94; };
+    return 47;
+};