cmake: corrected build issue with enums.awk and windows sort

the "-d" option was added to the sort command called from the enums.awk
script so that it would ignore "_" underscore characters in the names of
the codes; however, on Windows with the MinGW generator, the Windows
sort command is called, which does not support this option (options
start with a forward slash); unfortunately this option doesn't work as
desired anyway, so it was removed

enums.awk

@@ -191,8 +191,7 @@ BEGIN {
 		printf "\n" > "codes.txt"
 		for (i = 0; i < n; i++)
 		{
-			# 2010-04-28: added -d to ignore "_" in codes names
-			printf "%s = %d\n", c[i], i | "sort -d >> codes.txt"
+			printf "%s = %d\n", c[i], i | "sort >> codes.txt"
 		}
 
 		# output summary