Merge the changes need to compile on WinRT into trunk.

FossilOrigin-Name: 61360ca6ca3448477d5c662d3642beef6dd2079e

src/main.c

@@ -74,6 +74,15 @@ void (*sqlite3IoTrace)(const char*, ...) = 0;
 */
 char *sqlite3_temp_directory = 0;
 
+/*
+** If the following global variable points to a string which is the
+** name of a directory, then that directory will be used to store
+** all database files specified with a relative pathname.
+**
+** See also the "PRAGMA data_store_directory" SQL command.
+*/
+char *sqlite3_data_directory = 0;
+
 /*
 ** Initialize SQLite.  
 **
@@ -272,6 +281,18 @@ int sqlite3_shutdown(void){
   if( sqlite3GlobalConfig.isMallocInit ){
     sqlite3MallocEnd();
     sqlite3GlobalConfig.isMallocInit = 0;
+
+#ifndef SQLITE_OMIT_SHUTDOWN_DIRECTORIES
+    /* The heap subsystem has now been shutdown and these values are supposed
+    ** to be NULL or point to memory that was obtained from sqlite3_malloc(),
+    ** which would rely on that heap subsystem; therefore, make sure these
+    ** values cannot refer to heap memory that was just invalidated when the
+    ** heap subsystem was shutdown.  This is only done if the current call to
+    ** this function resulted in the heap subsystem actually being shutdown.
+    */
+    sqlite3_data_directory = 0;
+    sqlite3_temp_directory = 0;
+#endif
   }
   if( sqlite3GlobalConfig.isMutexInit ){
     sqlite3MutexEnd();