cgen: resolve local fn-ptr callees for variadic arg prep

The wwstage variadic call classification was name-keyed: a fn-ptr
FIELD call whose local base shadowed the current module name
(lib/log's log.println(log, args...)) picked the module fn's
signature — nfixed off by one, the fixed arg boxed into the gather,
the spread emitted as zeros — and a no-collision fn-ptr callee missed
the registry entirely, leaking the raw N_SPREAD as a single $0 word
(SIGSEGV / exit 255 in 8 of 11 logtest tests on the wwstage leg).
fnptrcalleetfn resolves a local fn-ptr callee (bare local or struct
field) to its N_TFN once, shared by the CALL-target choice,
callee_variadic_param (with the []T wrap registry params get from
installparams), calleecvariadic, and the widening param lookup, so
target and arg prep can never disagree. Graduates the #59.8 logtest
pin — DATABYTEID_DIVERGED-era M_DIVERGE count is now zero.

internal/wwfixture/types.ww

@@ -1,13 +1,13 @@
 package wwfixture;
 
 def protocolversion: i32 = 1;
-def corpuscount: i32 = 1238;
+def corpuscount: i32 = 1239;
 def errorcount: i32 = 314;
 def compilecount: i32 = 12;
-def runcount: i32 = 145;
+def runcount: i32 = 146;
 def runexitcount: i32 = 767;
-def nativecount: i32 = 2476;
-def corpushash: str = "a78db801f50ad02de11fed981bd6d9c2d67509e69a69615744f1b2ad3ef4814d";
+def nativecount: i32 = 2478;
+def corpushash: str = "369aca2f1c0081faf7297d8fa976a7374d97a07b76d2df079f7eea60660bda2a";
 
 type directive = enum i32 {
 	ERROR = 0,