In B source the argument to 'log' may be 0 upon start of simulation, allow recovery like in function 'ln'

src/spicelib/parser/ptfuncs.c

@@ -248,7 +248,7 @@ PTln(double arg)
 double
 PTlog(double arg)
 {
-    if (arg <= 0.0)
+    if (arg < 0.0)
         return (HUGE);
     return (log10(arg));
 }