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/r777_fprintf_file_int/case.ww

@@ -0,0 +1,27 @@
+//ww:run-exit 42
+// Migrated from 777_fmt_handle_run row fprintf_file_int.
+package main;
+import os;
+import fmt;
+import io;
+export fn main() i32 = {
+    let path: str = "wwfmth_777_a";
+    let fd: i32 = os.open(path, os.flag.RDWR | os.flag.CREATE | os.flag.TRUNC, 0o644: i32);
+    if (fd < 0) { return 90; };
+    let wr = fmt.fprintf(fd: io.file, "v={}\n", 42i64);
+    let nw: size = 0;
+    match (wr) {
+    case let n: size => { nw = n; };
+    case io.error => { return 91; };
+    };
+    os.close(fd);
+    let rd: i32 = os.open(path, os.flag.RDONLY, 0i32);
+    if (rd < 0) { return 92; };
+    let buf: [16]u8;
+    let n: i64 = os.read(rd, &buf[0], 16u64);
+    os.close(rd);
+    if (n != 5i64) { return 93; };
+    if (nw != 5: size) { return 94; };
+    if (buf[0] != 118u8 || buf[1] != 61u8 || buf[2] != 52u8 || buf[3] != 50u8 || buf[4] != 10u8) { return 95; };
+    return 42;
+};