lib/hash tests: hand-main plumbing -> assert (@test conversion B1)

signalled/fail() counters and run-loop plumbing removed; failure sites
become assert(!(cond)); table rows and @test fns 1:1. Bare mains stay
until the -T flip commit. Spec: .ai/drew-t2-conversion-spec.md.

lib/hash/adler32/adler32_test.ww

@@ -16,14 +16,14 @@ fn check(s: str, want: u32) void = {
 	let n: i32 = putstr(s, arr[0:256], 0);
 	let buf: []u8 = arr[0:n];
 	let got: u32 = adler32.sum32(buf);
-	if (got != want) { let _: i32 = 1/0; };
+	assert(!(got != want));
 };
 
 @test fn vec_empty() void = {
 	let arr: [1]u8;
 	let buf: []u8 = arr[0:0];
 	let h: u32 = adler32.sum32(buf);
-	if (h != 1u32) { let _: i32 = 1/0; };
+	assert(!(h != 1u32));
 };
 
 @test fn vec_helloworld() void = {