Move error simulation code from the sqlite3_os_init() functions into a wrapper.

FossilOrigin-Name: 67ad21abf88abb7a3e2eacddcaf1ab5d54149807

src/os.c

@@ -190,6 +190,17 @@ int sqlite3OsCloseFree(sqlite3_file *pFile){
   return rc;
 }
 
+/*
+** This function is a wrapper around the OS specific implementation of
+** sqlite3_os_init(). The purpose of the wrapper is to provide the
+** ability to simulate a malloc failure, so that the handling of an
+** error in sqlite3_os_init() by the upper layers can be tested.
+*/
+int sqlite3OsInit(void){
+  DO_OS_MALLOC_TEST(0);
+  return sqlite3_os_init();
+}
+
 /*
 ** The list of all registered VFS implementations.
 */