Fix regression in while loops inside each macros.

There was a specialization for `(while (not= nil _) ...)` that
was incorrect when the while loop regresses to a thunk.

src/boot/boot.janet

@@ -2115,7 +2115,7 @@
   (if-let [check (in module/cache fullpath)]
     check
     (do
-      (def loader (module/loaders mod-kind))
+      (def loader (if (keyword? mod-kind) (module/loaders mod-kind) mod-kind))
       (unless loader (error (string "module type " mod-kind " unknown")))
       (def env (loader fullpath args))
       (put module/cache fullpath env)

src/core/specials.c

@@ -630,7 +630,7 @@ static JanetSlot janetc_while(JanetFopts opts, int32_t argn, const Janet *argv)
         janetc_scope(&tempscope, c, JANET_SCOPE_FUNCTION, "while-iife");
 
         /* Recompile in the function scope */
-        cond = janetc_value(subopts, argv[0]);
+        cond = janetc_value(subopts, condform);
         if (!(cond.flags & JANET_SLOT_CONSTANT)) {
             /* If not an infinite loop, return nil when condition false */
             janetc_emit_si(c, ifjmp, cond, 2, 0);