Slight problem with ndisgen and ndiscvt

Hi

There is a slight problem with ndisgen and ndiscvt when the filename of the
.sys-file starts with a number (such as 3C154G72.sys).
The produced header file contains variable declarations which starts with a number,
such as extern unsigned char 3C154G72_sys_drv_data_start[] which results in 
several "syntax error before numeric constant" during compilation.

While this can be solved simply by renaming the .sys-file, that solution might not
be obvious to ordinary users. 
Here is a  small patch which adds a "ndis_" prefix to drv_data_start and 
related variables. This will allow filesnames which starts with a number. 
Maybe even more care should be taken to make sure there are no spaces or 
other "strange" characters in the name.

   Fredrik Lindberg