Make `make clean` remove all files created when running `make check`. More specifically: remove also `obj/build.h` and `bench/data/block413567.raw.h` as part of `make clean`.

Before this patch:

```bash
$ git clone https://github.com/bitcoin/bitcoin.git
$ cd bitcoin/
$ ./autogen.sh
$ ./configure
$ cp -r ../bitcoin ../bitcoin-before-make
$ make check
$ make clean
$ cp -r ../bitcoin ../bitcoin-after-make-and-make-clean
$ cd ..
$ diff -rq bitcoin-before-make/ bitcoin-after-make-and-make-clean/ | grep -E "^Only in bitcoin-after-make-and-make-clean/" | grep -v dirstamp
Only in bitcoin-after-make-and-make-clean/src/bench/data: block413567.raw.h
Only in bitcoin-after-make-and-make-clean/src/obj: build.h
$
```

After this patch:

```bash
$ git clone https://github.com/bitcoin/bitcoin.git
$ cd bitcoin/
$ ./autogen.sh
$ ./configure
$ cp -r ../bitcoin ../bitcoin-before-make
$ make check
$ make clean
$ cp -r ../bitcoin ../bitcoin-after-make-and-make-clean
$ cd ..
$ diff -rq bitcoin-before-make/ bitcoin-after-make-and-make-clean/ | grep -E "^Only in bitcoin-after-make-and-make-clean/" | grep -v dirstamp
$
```

# on master
make
make clean
ls src/bench/data
# block413567.raw.h
ls src/obj
# build.h

# with this patch applied
make
make clean
ls src/bench/data
# <nothing>
ls src/obj
# <nothing>