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/os_os2.c

@@ -1111,16 +1111,7 @@ int sqlite3_os_init(void){
     os2Randomness,     /* xRandomness */
     os2Sleep,          /* xSleep */
     os2CurrentTime,    /* xCurrentTime */
-    os2GetLastError    /* xGetLastError */
-    0,                 /* xShmOpen */
-    0,                 /* xShmSize */
-    0,                 /* xShmPush */
-    0,                 /* xShmPull */
-    0,                 /* xShmLock */
-    0,                 /* xShmClose */
-    0,                 /* xShmDelete */
-    0,                 /* xRename */
-    0,                 /* xCurrentTimeInt64 */
+    os2GetLastError,   /* xGetLastError */
   };
   sqlite3_vfs_register(&os2Vfs, 1);
   initUconvObjects();