PCH: remove headers which are actually could be changed (#950)

src/common/hwnd_data_cache.h

@@ -4,6 +4,8 @@
 #include <string>
 #include <Windows.h>
 
+#include "common.h"
+
 class HWNDDataCache {
 public:
   WindowAndProcPath get_window_and_path(HWND hwnd);

src/common/monitors.cpp

@@ -1,4 +1,6 @@
 #include "pch.h"
+
+#include "common.h"
 #include "monitors.h"
 
 bool operator==(const ScreenSize& lhs, const ScreenSize& rhs) {

src/common/pch.h

@@ -23,4 +23,3 @@
 #include <string>
 #include <vector>
 
-#include "common.h"