wcc: drop @test fns from non-T builds, both stages (harec check.c:3941)

Splice @test N_FNDECLs out of the unit after the body-check passes,
mirroring harec's checked-but-not-emitted: a broken @test body still
errors loudly in non-T; @test-free units are emission-unchanged.
910/997 table rows pin keep/test x non-T/-T, head+consecutive unlink,
undef-body reject, and plain-calls-dropped loud link-fail. w6c+wwdump
combined.ww regen. (#6-team)

test/wcc/data/attest_calldropped.ww

@@ -0,0 +1,18 @@
+// #6 fixture: a plain fn (the entry) CALLS a @test fn. In non-T the
+// @test def is spliced out but the CALL survives — harec-faithful: the
+// reference is left DANGLING and fails LOUDLY at link, never a silent
+// mis-link (ref/harec/src/check.c:3941 drops the decl; the call site's
+// symbol is never satisfied). Built non-T then linked: the link MUST
+// fail with an undefined reference to the dropped @test symbol (910
+// linkfail probe). No -T variant — a user main is -T-rejected (910).
+
+package data;
+
+@test fn calldropped_test() void = {
+	let a: i32 = 1;
+};
+
+export fn main() i32 = {
+	calldropped_test();
+	return 0;
+};