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_unread/case.ww

@@ -0,0 +1,31 @@
+//ww:run-exit 55
+// Migrated from 778_bufio_vstream_run row stream_unread.
+package main;
+import os;
+import bufio;
+import memio;
+import io;
+export fn main() i32 = {
+    let raw: [4]u8;
+    raw[0]=88u8; raw[1]=89u8; raw[2]=90u8;
+    let mst: memio.stream = memio.dynamicfrom(raw[0:3]);
+    let vs: io.stream = &mst.vt;
+    let rbuf: [4]u8;
+    let wbuf: [4]u8;
+    let b: bufio.stream = bufio.init(vs, rbuf[0:4], wbuf[0:4]);
+    let bvs: io.stream = &b.vt;
+    let out: [4]u8;
+    let rd = io.read(bvs, out[0:3]);
+    let n: size = 0;
+    if (rd is size) { n = rd as size; };
+    if (n != 3: size || out[0] != 88u8 || out[2] != 90u8) { return 81; };
+    let push: [2]u8;
+    push[0]=88u8; push[1]=89u8;
+    bufio.unread(&b, push[0:2]);
+    let out2: [2]u8;
+    let rd2 = io.read(bvs, out2[0:2]);
+    let n2: size = 0;
+    if (rd2 is size) { n2 = rd2 as size; };
+    if (n2 != 2: size || out2[0] != 88u8 || out2[1] != 89u8) { return 82; };
+    return 55;
+};