Optional F parm in checksum functions

[Charles Dye]

C:\>ver /r

TCC  19.00.25  Windows 7 [Version 6.1.7601]
TCC Build 25  Windows 7 Build 7601  Service Pack 1
Registered to Charles Dye

C:\>echo %@crc32[f,Build.txt]
-1

C:\>echo %@crc32[Build.txt]
0015C048

C:\>echo %@md5[f,Build.txt]
-1

C:\>echo %@md5[Build.txt]
C6E6AE3A9DD9D26382F272CAFFC0267F

C:\>

Likewise the @SHAxxx functions, though they are not documented as supporting the F parameter. I have no strong opinion on whether the code should be fixed to match the docs or vice versa. (This is not new to v19; v18 is the same; possibly earlier versions too, I didn't check.)