Add the xShmRelease() method to the VFS. The os_unix.c implementation of

the shared memory logic is still non-functional.

FossilOrigin-Name: ed715b47c5f7657fbf901805981867898054b14d

src/test_devsym.c

@@ -93,15 +93,6 @@ static sqlite3_vfs devsym_vfs = {
   devsymRandomness,         /* xRandomness */
   devsymSleep,              /* xSleep */
   devsymCurrentTime,        /* xCurrentTime */
-  0,                        /* xShmOpen */
-  0,                        /* xShmSize */
-  0,                        /* xShmPush */
-  0,                        /* xShmPull */
-  0,                        /* xShmLock */
-  0,                        /* xShmClose */
-  0,                        /* xShmDelete */
-  0,                        /* xRename */
-  0                         /* xCurrentTimeInt64 */
 };
 
 static sqlite3_io_methods devsym_io_methods = {