Backport a subset of upstream c++11 fixes.
--- a/htmacho.cc
+++ b/htmacho.cc
@@ -146,7 +146,7 @@ void ht_macho::init(Bounds *b, File *f, format_viewer_if **ifs, ht_format_group
 				break;
 			case MACHO_CPU_TYPE_I386:
 				switch (c->flavor) {
-				case -1:
+				default:
 					createHostStruct(&c->state, MACHO_I386_THREAD_STATE_struct, image_endianess);
 					break;
 				}
--- a/htmachohd.cc
+++ b/htmachohd.cc
@@ -313,7 +313,7 @@ static ht_view *htmachoheader_init(Bounds *b, File *file, ht_format_group *group
 				switch (macho_shared->header.cputype) {
 				case MACHO_CPU_TYPE_I386:
 					switch (c->flavor) {
-					case -1:
+					default:
 						m->add_staticmask_ptable(macho_i386_thread_state, ofs+4*4/*4 32bit words in thread_header*/, isbigendian);
 						break;
 					}
--- a/io/types.h
+++ b/io/types.h
@@ -87,8 +87,8 @@ union htmsg_param {
 };
 
 struct htmsg {
-	int msg;
-	int type;
+	unsigned int msg;
+	unsigned int type;
 	htmsg_param data1;
 	htmsg_param data2;
 };