Fix some unitialized variables.

Fixes https://gitlab.com/kicad/code/kicad/issues/4477

Fixes https://gitlab.com/kicad/code/kicad/issues/4473

pcbnew/drc/drc_clearance_test_functions.cpp

@@ -162,7 +162,7 @@ void DRC::doTrackDrc( BOARD_COMMIT& aCommit, TRACK* aRefSeg, TRACKS::iterator aS
     {
         VIA *refvia = static_cast<VIA*>( aRefSeg );
         int viaAnnulus = ( refvia->GetWidth() - refvia->GetDrill() ) / 2;
-        int minAnnulus;
+        int minAnnulus = 0;
 
         for( DRC_SELECTOR* selector : matched )
         {

pcbnew/drc/drc_rule.h

@@ -34,6 +34,14 @@ class BOARD_ITEM;
 
 class DRC_RULE
 {
+public:
+    DRC_RULE() :
+            m_Clearance( 0 ),
+            m_AnnulusWidth( 0 ),
+            m_TrackWidth( 0 ),
+            m_Hole( 0 )
+    { }
+
 public:
     wxString m_Name;
 
@@ -49,6 +57,11 @@ public:
 
 class DRC_SELECTOR
 {
+public:
+    DRC_SELECTOR() :
+            m_Priority( 1 )
+    { }
+
 public:
     std::vector<NETCLASSPTR>  m_MatchNetclasses;
     std::vector<KICAD_T>      m_MatchTypes;
@@ -57,8 +70,6 @@ public:
 
     int                       m_Priority;       // 0 indicates automatic priority generation
     DRC_RULE*                 m_Rule;
-
-public:
 };