Finish remaining fixes for the JS backend

The JS backend doesn't support capi calling convention for the time
being. This patch delivers the remaining fixes, and is indeed tested
to work via a ghc validate pipeline.

lib/Data/Time/Clock/Internal/CTimespec.hsc

@@ -30,11 +30,22 @@ instance Storable CTimespec where
         #{poke struct timespec, tv_sec } p s
         #{poke struct timespec, tv_nsec} p ns
 
+#if defined(javascript_HOST_ARCH)
+
+foreign import ccall unsafe "time.h clock_gettime"
+    clock_gettime :: ClockID -> Ptr CTimespec -> IO CInt
+foreign import ccall unsafe "time.h clock_getres"
+    clock_getres :: ClockID -> Ptr CTimespec -> IO CInt
+
+#else
+
 foreign import capi unsafe "time.h clock_gettime"
     clock_gettime :: ClockID -> Ptr CTimespec -> IO CInt
 foreign import capi unsafe "time.h clock_getres"
     clock_getres :: ClockID -> Ptr CTimespec -> IO CInt
 
+#endif
+
 -- | Get the resolution of the given clock.
 clockGetRes :: ClockID -> IO (Either Errno CTimespec)
 clockGetRes clockid = alloca $ \ptspec -> do

lib/Data/Time/Clock/Internal/CTimeval.hs

-{-# LANGUAGE CApiFFI #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE Safe #-}
+#if !defined(javascript_HOST_ARCH)
+{-# LANGUAGE CApiFFI #-}
+#endif
 
 module Data.Time.Clock.Internal.CTimeval where
 
@@ -24,8 +26,16 @@ instance Storable CTimeval where
         pokeElemOff (castPtr p) 0 s
         pokeElemOff (castPtr p) 1 mus
 
+#if defined(javascript_HOST_ARCH)
+
+foreign import ccall unsafe "sys/time.h gettimeofday" gettimeofday :: Ptr CTimeval -> Ptr () -> IO CInt
+
+#else
+
 foreign import capi unsafe "sys/time.h gettimeofday" gettimeofday :: Ptr CTimeval -> Ptr () -> IO CInt
 
+#endif
+
 -- | Get the current POSIX time from the system clock.
 getCTimeval :: IO CTimeval
 getCTimeval =