core: Removing duplicated code

Some variable are assigned during initialization and another time with
the same value a very few later.

That's clearly useless and could lead to an error if only one is changed.
core: Don't leak memory if error is unknown

If error is unknown, the "return 1" call was not freeing error which was
malloced at the beginning of the function.
core: Insure "il" is initialized in all cases

Prior this commit, "il" was not initialized and check_int() was supposed
to setup it's value before usage.

In fact, check_int() can let "il" uninitialized leading to a dprint()
with a unintialized value.
Update for RDMA io engine's compatibility

Since the RDMA engine is not able to be successfully compiled, this
patch accommodates it to the upstream version of fio.

Signed-off-by: Jens Axboe <axboe@kernel.dk>