ww: lib tests run via -T test mode; bare mains retired (closes @test conversion)

'ww test' gains the istest build path (-T injection in build_one/
buildone) and do_test/dotest accept -I, mirroring do_run - both twins.
The 35 converted lib tests drop their interim bare mains (-T
synthesizes the entry from @test fns and rejects a user main); their
35 C run-drivers flip 'ww run' -> 'ww test'; 989_lib_byteid compiles
lib tests under -T (8 user-main probe fixtures stay non-T, gated on
the fixture field). Abort-on-first-failure stands until the deferred
record-and-continue harness lands with the multi-package arc.

lib/hash/adler32/adler32_test.ww

@@ -43,12 +43,3 @@ fn check(s: str, want: u32) void = {
 	check("'The central enemy of reliability is complexity.' - Geer et al",
 		3170309588u32);
 };
-
-export fn main() i32 = {
-	vec_empty();
-	vec_helloworld();
-	vec_hareiscool();
-	vec_bdale();
-	vec_geer();
-	return 0;
-};

lib/hash/crc16/crc16_test.ww

@@ -49,12 +49,3 @@ fn check(s: str, ccitt: u16, cmda: u16, dect: u16, ansi: u16) void = {
 	check("I want peace and I'm willing to fight for it. -- Harry Truman",
 		0xB0E8u16, 0xFE1Fu16, 0x4659u16, 0x5062u16);
 };
-
-export fn main() i32 = {
-	vec_empty();
-	vec_truman();
-	vec_animals();
-	vec_twain();
-	vec_peace();
-	return 0;
-};

lib/hash/crc32/crc32_test.ww

@@ -52,13 +52,3 @@ fn check(s: str, ieee: u32, cast: u32, koop: u32) void = {
 	check("GNU's not UNIX",
 		224734747u32, 200511816u32, 332335539u32);
 };
-
-export fn main() i32 = {
-	vec_empty();
-	vec_fire();
-	vec_setfire();
-	vec_blm();
-	vec_unix();
-	vec_gnu();
-	return 0;
-};

lib/hash/crc64/crc64_test.ww

@@ -55,14 +55,3 @@ fn check(s: str, ecma: u64, iso: u64) void = {
 	check("Black lives matter",
 		0x159BB7B6086BF47Eu64, 0xC218CBB390CF44EBu64);
 };
-
-export fn main() i32 = {
-	vec_empty();
-	vec_oscar();
-	vec_hegel();
-	vec_chapelain();
-	vec_unix();
-	vec_gnu();
-	vec_blm();
-	return 0;
-};

lib/hash/siphash/siphash_test.ww

@@ -68,10 +68,3 @@ fn putstr(s: str, into: []u8, off: i32) i32 = {
 	let empty: [1]u8;
 	assert(!(siphash.sum24(key[0:16], empty[0:0]) != 0x2A51AE0682925836u64));
 };
-
-export fn main() i32 = {
-	refkey_msgN();
-	ascii();
-	empty();
-	return 0;
-};