ht: fix gcc7 compilation

pkgs/applications/editors/ht/default.nix

···
 
   hardeningDisable = [ "format" ];
 
+  patches = [ ./gcc7.patch ];
+
   meta = with lib; {
     description = "File editor/viewer/analyzer for executables";
     homepage = http://hte.sourceforge.net;

pkgs/applications/editors/ht/gcc7.patch

···
+--- ht-2.1.0.org/htapp.cc	2014-09-14 16:55:26.000000000 +0100
++++ ht-2.1.0/htapp.cc	2018-03-10 12:48:07.158533800 +0000
+@@ -3023,7 +3023,7 @@
+ {
+ 	uint a = 2;
+ 	uint b = u/a;
+-	while (abs(a - b) > 1) {
++	while (abs((int)(a - b)) > 1) {
+ 		a = (a+b)/2;
+ 		b = u/a;
+         }