commit: Support #!, to allow XEmacs to be called as a script interpreter.

[Stephen J. Turnbull]

Vin Shelton writes:

 > >  Support #!, to allow XEmacs to be called as a script interpreter.
 > 
 > doesn't work with native Windows XEmacs:

 > Please figure out a way to support this in the baroque Windows
 > configuration process.

What do you mean by "support"?  Does native Windows actually support
shebang at all?

Isn't the right way to support this to #ifdef it out on native
Windows?