sim65 suppress uninitialized variable warning

the EOF check was protecting uninitialized Val2 but the compiler can't figure that out

src/sim65/main.c

@@ -189,6 +189,7 @@ static unsigned char ReadProgramFile (void)
     }
 
     /* Get load address */
+    Val2 = 0; /* suppress uninitialized variable warning */
     if (((Val = fgetc(F)) == EOF) ||
         ((Val2 = fgetc(F)) == EOF)) {
         Error ("'%s': Header missing load address", ProgramFile);