Apple2: Provide a way to get directory file count

The information is available in the directory key block.
Providing it to the user as soon as opendir() is done
can save them costly code.

include/apple2.h

@@ -232,6 +232,11 @@ struct tm* __fastcall__ gmtime_dt (const struct datetime* dt);
 time_t __fastcall__ mktime_dt (const struct datetime* dt);
 /* Converts a ProDOS date/time structure to a time_t UNIX timestamp */
 
+typedef struct DIR DIR;
+
+unsigned int __fastcall__ dir_file_count(DIR *dir);
+/* Returns the number of active files in a ProDOS directory */
+
 #if !defined(__APPLE2ENH__)
 unsigned char __fastcall__ allow_lowercase (unsigned char onoff);
 /* If onoff is 0, lowercase characters printed to the screen via STDIO and

include/dirent.h

@@ -147,7 +147,5 @@ void __fastcall__ seekdir (DIR* dir, long offs);
 
 void __fastcall__ rewinddir (DIR* dir);
 
-
-
 /* End of dirent.h */
 #endif