test: port 839_xmod_nominal_typeeqast to corpus fixtures

839_xmod_nominal_typeeqast.c -> r839_xmod_nominal_match (run-exit 42),
  r839_xmod_a6_concrete (run), r839_xmod_incompat_concrete (error
  'not assignable'), r839_xmod_distinct_alias (error 'ambiguous
  without nominal layout').

r839_xmod_nominal_match enters DATABYTEID_DIVERGED: the carrier waived
byte-id for the pre-existing cross-module tagged-return spill
divergence; the DIVERGED row makes it loud-on-fix instead. The
typeeqast-layer discriminator itself stays with the lib byteid gate
(test/byteid/libbyteid_test.ww), as the carrier documented.

internal/wwfixture/types.ww

@@ -1,13 +1,13 @@
 package wwfixture;
 
 def protocolversion: i32 = 1;
-def corpuscount: i32 = 1669;
-def errorcount: i32 = 339;
+def corpuscount: i32 = 1673;
+def errorcount: i32 = 341;
 def compilecount: i32 = 18;
-def runcount: i32 = 206;
-def runexitcount: i32 = 1106;
-def nativecount: i32 = 3338;
-def corpushash: str = "2c2ef7841c6da289337a72816041bdc594fa84da18d4f1e11327db3d578e1d14";
+def runcount: i32 = 207;
+def runexitcount: i32 = 1107;
+def nativecount: i32 = 3346;
+def corpushash: str = "a071db5169fe671d40b72d9967caaea053b505f300e64f787f3627ca0f340f5c";
 
 type directive = enum i32 {
 	ERROR = 0,