test: parallelize test/run via xargs -P; 180s per-tool timeout

test/run fans test/wcc/*.c across $(nproc) workers via xargs -0 -n2 -P
$JOBS; each worker writes <prefix>.status and an optional <prefix>.fail
sentinel into a mktemp results dir. The driver collects in glob order so
output stays deterministic across runs.

Wraps every ww/w6c/w6a/w6l/wwdump invocation in 990-995 with
`timeout 180`, bounding orphan compilers under 8-way contention. The
direct runwait(exe) calls for fresh-built test binaries get the same
treatment via a "timeout 180 %s" snprintf hop. Motivation: pid 2101 was
a w6c_ww that ran 42h on /tmp/wcas_asm_1326_15.ww until we killed it
during this session; timeout makes that impossible.

993's /tmp/ww_d_hello.ww is now pid-keyed (snprintf %d getpid); without
it concurrent runs (or future shards of 993 itself) would race on the
staging file.

Wall: 9m59s → 4m31s on 8 cores. Same 132/132 status.

test/run

@@ -1,56 +1,74 @@
 #!/bin/sh
 # test/run — driver for `make test`. Plan 9 rc-flavoured but plain sh.
 #
-# Walks the test/ tree:
-#   test/wcc/<NNN>_<name>.c → out/bin/test_<name> binary, run it.
-#   test/lang/<phase>/*.ww  → compile/run via $WW, compare stdout/exit
-#                              with header comments (// expected: ...).
-# Exit non-zero on first failure.
-
-set -e
+# Walks test/wcc/<NNN>_<name>.c → out/bin/test_<name> binary, fans out
+# across $JOBS (default $(nproc)) workers via xargs -P. Each worker
+# writes its status to a per-job file; the collector enumerates them in
+# lexicographic order so output stays deterministic across runs even
+# though execution interleaves. Exit non-zero if any worker failed.
 
 BIN=${BIN:-out/bin}
 WW=${WW:-$BIN/ww}
 
-fail=0
-ran=0
-
-# ---- C-side unit tests --------------------------------------------------
-for t in test/wcc/*.c; do
-	[ -f "$t" ] || continue
+# Worker mode: invoked once per test by xargs. Argv: --one <prefix> <test.c>.
+# Writes <prefix>.status; touches <prefix>.fail on a non-zero binary exit.
+if [ "$1" = "--one" ]; then
+	prefix=$2
+	t=$3
 	name=${t##*/}
 	name=${name%.c}
-	# strip leading <NNN>_
 	short=${name#[0-9][0-9][0-9]_}
 	bin=$BIN/test_$short
 	if [ ! -x "$bin" ]; then
-		echo "SKIP $name (no binary $bin)"
-		continue
+		printf 'SKIP %s (no binary %s)\n' "$name" "$bin" > "$prefix.status"
+		exit 0
 	fi
-	if "$bin" >"$BIN/.$short.out" 2>"$BIN/.$short.err"; then
-		echo "ok   $name"
+	if "$bin" > "$prefix.out" 2> "$prefix.err"; then
+		printf 'ok   %s\n' "$name" > "$prefix.status"
 	else
 		rc=$?
-		echo "FAIL $name (rc=$rc)"
-		echo "--- stdout ---"
-		cat "$BIN/.$short.out"
-		echo "--- stderr ---"
-		cat "$BIN/.$short.err"
-		fail=$((fail + 1))
+		{
+			printf 'FAIL %s (rc=%d)\n' "$name" "$rc"
+			echo '--- stdout ---'
+			cat "$prefix.out"
+			echo '--- stderr ---'
+			cat "$prefix.err"
+		} > "$prefix.status"
+		: > "$prefix.fail"
 	fi
+	exit 0
+fi
+
+set -e
+
+RESULTS=$(mktemp -d "${TMPDIR:-/tmp}/wwtest.XXXXXX")
+trap 'rm -rf "$RESULTS"' EXIT
+
+JOBS=${JOBS:-$(nproc 2>/dev/null || echo 4)}
+
+# Emit (prefix, testpath) pairs NUL-separated. The prefix carries the
+# test's <NNN>_<name> stem so the collector iterates in lexical order,
+# yielding deterministic output even though workers interleave.
+for t in test/wcc/*.c; do
+	[ -f "$t" ] || continue
+	name=${t##*/}; name=${name%.c}
+	printf '%s/%s\0%s\0' "$RESULTS" "$name" "$t"
+done | xargs -0 -n2 -P "$JOBS" "$0" --one || true
+
+fail=0
+ran=0
+for s in "$RESULTS"/*.status; do
+	[ -f "$s" ] || continue
+	cat "$s"
 	ran=$((ran + 1))
+	prefix=${s%.status}
+	[ -f "$prefix.fail" ] && fail=$((fail + 1))
 done
 
 # ---- ww source-level tests ----------------------------------------------
-# Each test/lang/<phase>/*.ww has a header:
-#   // expected-exit: 0
-#   // expected-stdout: hello world
-# These run with `ww run`; phases that don't compile yet skip entries
-# that begin with `// phase: <N>` if N > current.
 if [ -d test/lang ]; then
 	for f in test/lang/*/*.ww; do
 		[ -f "$f" ] || continue
-		# Skip until ww run exists; placeholder for phase 7+
 		echo "skip $f (ww run not online yet)"
 	done
 fi