Convert some extern variables to static, Windows code

Similar to 720b0ea, discovered by MinGW.

Author: petere

src/bin/pg_upgrade/parallel.c

@@ -24,7 +24,7 @@ static int	parallel_jobs;
  *	it can be passed to WaitForMultipleObjects().  We use two arrays
  *	so the thread_handles array can be passed to WaitForMultipleObjects().
  */
-HANDLE	   *thread_handles;
+static HANDLE *thread_handles;
 
 typedef struct
 {
@@ -42,11 +42,11 @@ typedef struct
 	char	   *old_tablespace;
 } transfer_thread_arg;
 
-exec_thread_arg **exec_thread_args;
-transfer_thread_arg **transfer_thread_args;
+static exec_thread_arg **exec_thread_args;
+static transfer_thread_arg **transfer_thread_args;
 
 /* track current thread_args struct so reap_child() can be used for all cases */
-void	  **cur_thread_args;
+static void **cur_thread_args;
 
 DWORD		win32_exec_prog(exec_thread_arg *args);
 DWORD		win32_transfer_all_new_dbs(transfer_thread_arg *args);

src/bin/pgevent/pgevent.c

@@ -15,14 +15,14 @@
 #include <olectl.h>
 
 /* Global variables */
-HANDLE		g_module = NULL;	/* hModule of DLL */
+static HANDLE g_module = NULL;	/* hModule of DLL */
 
 /*
  * The event source is stored as a registry key.
  * The maximum length of a registry key is 255 characters.
  * http://msdn.microsoft.com/en-us/library/ms724872(v=vs.85).aspx
  */
-char		event_source[256] = DEFAULT_EVENT_SOURCE;
+static char event_source[256] = DEFAULT_EVENT_SOURCE;
 
 /* Prototypes */
 HRESULT		DllInstall(BOOL bInstall, LPCWSTR pszCmdLine);

src/common/restricted_token.c

@@ -26,7 +26,7 @@
 #ifdef WIN32
 
 /* internal vars */
-char	   *restrict_env;
+static char *restrict_env;
 
 /* Windows API define missing from some versions of MingW headers */
 #ifndef  DISABLE_MAX_PRIVILEGE

src/interfaces/libpq/win32.c

@@ -231,7 +231,7 @@ LookupWSErrorMessage(DWORD err, char *dest)
 }
 
 
-struct MessageDLL
+static struct MessageDLL
 {
 	const char *dll_name;
 	void	   *handle;