wear_ui: Remove dead 'self' and 'progress_t'.

They were once used for progress_thread() that's pthread_create'd by
WearRecoveryUI::Init(). They have become dead since the removal of
progress_thread() (commit ad8b5a6c11).

Also add the missing include of <pthread.h> for pthread_mutex_lock().

Test: lunch a watch target and `m recoveryimage`.
Change-Id: I748cf4511434ac4ce97dddf89b0e42e68a5da04b

wear_ui.cpp

@@ -18,6 +18,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <pthread.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <string.h>
@@ -38,11 +39,6 @@
 #include "common.h"
 #include "device.h"
 
-// There's only (at most) one of these objects, and global callbacks
-// (for pthread_create, and the input event system) need to find it,
-// so use a global variable.
-static WearRecoveryUI* self = NULL;
-
 // Return the current time as a double (including fractions of a second).
 static double now() {
   struct timeval tv;
@@ -63,8 +59,6 @@ WearRecoveryUI::WearRecoveryUI()
   touch_screen_allowed_ = true;
 
   for (size_t i = 0; i < 5; i++) backgroundIcon[i] = NULL;
-
-  self = this;
 }
 
 int WearRecoveryUI::GetProgressBaseline() const {

wear_ui.h

@@ -68,8 +68,6 @@ class WearRecoveryUI : public ScreenRecoveryUI {
   const char* const* menu_headers_;
   int menu_start, menu_end;
 
-  pthread_t progress_t;
-
   void draw_background_locked() override;
   void draw_screen_locked() override;