Rearrange some static assertions for consistency

Put lengthof first.

Reported-by: Peter Smith <smithpb2250@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAHut+PsUDMySVRuRc=h+P5N3+=TGvj4W_mi32XXg9dt4o-BXbA@mail.gmail.com

src/backend/executor/execExprInterp.c

@@ -496,7 +496,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		&&CASE_EEOP_LAST
 	};
 
-	StaticAssertStmt(EEOP_LAST + 1 == lengthof(dispatch_table),
+	StaticAssertStmt(lengthof(dispatch_table) == EEOP_LAST + 1,
 					 "dispatch_table out of whack with ExprEvalOp");
 
 	if (unlikely(state == NULL))

src/backend/utils/cache/syscache.c

@@ -1068,7 +1068,7 @@ InitCatalogCache(void)
 {
 	int			cacheId;
 
-	StaticAssertStmt(SysCacheSize == (int) lengthof(cacheinfo),
+	StaticAssertStmt(lengthof(cacheinfo) == SysCacheSize,
 					 "SysCacheSize does not match syscache.c's array");
 
 	Assert(!CacheInitialized);