Drop unsafe from PQconsumeInput FFI import

Some paths in PQconsumeInput can go into blocking I/O calls.

This has really bad interactions with GC; the RTS ends up waiting on IO
(potentially, network) before being able to start Garbage Collection --
meanwhile, any Haskell mutation is blocked all this time.

See the related research in: https://gitlab.haskell.org/ghc/ghc/-/issues/18415

Regardless of further issues in GHC RTS -- this call *must not* be marked "unsafe".

Author: ulidtko

src/Database/PostgreSQL/LibPQ.hsc

@@ -2510,7 +2510,7 @@ foreign import ccall        "libpq-fe.h PQcancel"
 foreign import ccall unsafe "libpq-fe.h PQnotifies"
     c_PQnotifies :: Ptr PGconn -> IO (Ptr Notify)
 
-foreign import ccall unsafe "libpq-fe.h PQconsumeInput"
+foreign import ccall        "libpq-fe.h PQconsumeInput"
     c_PQconsumeInput :: Ptr PGconn -> IO CInt
 
 foreign import ccall unsafe "libpq-fe.h PQisBusy"