Fix some warnings in unix/mmap.c
                
                Brought to you by:
                
                    alsterg
                    
                
            
            
        
        
        
    While creating a FreeBSD port of tcl-mmap, I endeavored to fix as many warnings as I could. Attached is the patch. Please, consider merging it into your next release. The code now compiles cleanly with the following gcc flags:
-Wall -Wno-format-y2k -W -Wno-unused-parameter -Wstrict-prototypes -Wmissing-prototypes -Wpointer-arith -Wno-uninitialized -Wno-pointer-sign
Thank you!
Fix some of the warnings in the source.