Fix an unchecked return - change was back-migrated

from version 3.7.6.3 of sqlite.c from upstream.

ext/sqlite3/libsqlite/sqlite3.c

@@ -17818,7 +17818,7 @@ SQLITE_API sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
   sqlite3_int64 priorLimit;
   sqlite3_int64 excess;
 #ifndef SQLITE_OMIT_AUTOINIT
-  sqlite3_initialize();
+  if( sqlite3_initialize() ) return 0;
 #endif
   sqlite3_mutex_enter(mem0.mutex);
   priorLimit = mem0.alarmThreshold;