pkg(8): Remove a double word in a source code comment

- s/that that/that/

MFC after:	3 days

usr.sbin/pkg/pkg.c

@@ -1230,10 +1230,10 @@ main(int argc, char *argv[])
 		fetchDebug = 1;
 
 	if ((bootstrap_only && force) || access(pkgpath, X_OK) == -1) {
-		/* 
+		/*
 		 * To allow 'pkg -N' to be used as a reliable test for whether
 		 * a system is configured to use pkg, don't bootstrap pkg
-		 * when that that option is passed.
+		 * when that option is passed.
 		 */
 		if (activation_test)
 			errx(EXIT_FAILURE, "pkg is not installed");