JS: foreign CLOCK_REALTIME shouldn't use CApiFFI

In ghc/packages/time@226562b1, detection of the foreign value for CLOCK_REALTIME has been changed as follows to accommodate the Wasm backend:

-clock_REALTIME :: ClockID
-clock_REALTIME = #{const CLOCK_REALTIME}
+foreign import capi unsafe "time.h value CLOCK_REALTIME" clock_REALTIME :: ClockID

It broke the JS backend which doesn't support the CApiFFI.

The change must be conditionally reverted for the JS target and the submodule must be updated.