Three more valgrind discoveries:

- readfile.c, version patch for new toolsettings used a malloc, using
  unitialized variables
- despgraph, another malloc changed to calloc
- timer code for render ESC: unitialized variable in struct

source/blender/blenkernel/intern/depsgraph.c

@@ -666,18 +666,10 @@ DagNode * dag_add_node (DagForest *forest, void * fob)
 {
 	DagNode *node;
 		
-	node = MEM_mallocN(sizeof(DagNode),"DAG node");
+	node = MEM_callocN(sizeof(DagNode),"DAG node");
 	if (node) {
 		node->ob = fob;
 		node->color = DAG_WHITE;
-		node->BFS_dist = 0;		
-		node->DFS_dist = 0;		
-		node->DFS_dvtm = 0;		
-		node->DFS_fntm = 0;
-		node->child = NULL;
-		node->next = NULL;
-		node->first_ancestor = NULL;
-		node->ancestor_count = 0;
 
 		if(ugly_hack_sorry) node->type = GS(((ID *) fob)->name);	// sorry, done for pose sorting
 		if (forest->numNodes) {

source/blender/blenloader/intern/readfile.c

@@ -5197,7 +5197,7 @@ static void do_versions(FileData *fd, Library *lib, Main *main)
 
 		while(sce){
 			if(sce->toolsettings == NULL){
-				sce->toolsettings = MEM_mallocN(sizeof(struct ToolSettings),"Tool Settings Struct");	
+				sce->toolsettings = MEM_callocN(sizeof(struct ToolSettings),"Tool Settings Struct");	
 				sce->toolsettings->cornertype=0;
 				sce->toolsettings->degr = 90; 
 				sce->toolsettings->step = 9;

source/blender/src/renderwin.c

@@ -1016,8 +1016,7 @@ static void end_test_break_callback()
 {
 	struct itimerval tmevalue;
 
-	tmevalue.it_value.tv_sec = 0;
-	tmevalue.it_value.tv_usec = 0;
+	memset(&tmevalue, 0, sizeof(struct itimerval));
 
 	setitimer(ITIMER_REAL, &tmevalue, 0);
 	signal(SIGALRM, SIG_IGN);