check.h: remove obsolete header

Since we switched from autotools to Meson in commit
94592c1406, we don't need to include
`config.h` early to properly enable large file support.  Meson passes
the required macros on the compiler command line instead of defining
them in `config.h`.

This means we can include `config.h` at any time, whenever we want to
check its macros, and there are no ordering constraints.

src/neighbor/Glue.cxx

@@ -17,7 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "config.h"
 #include "Glue.hxx"
 #include "Registry.hxx"
 #include "Explorer.hxx"

src/neighbor/Glue.hxx

@@ -20,7 +20,6 @@
 #ifndef MPD_NEIGHBOR_ALL_HXX
 #define MPD_NEIGHBOR_ALL_HXX
 
-#include "check.h"
 #include "util/Compiler.h"
 #include "thread/Mutex.hxx"
 

src/neighbor/plugins/SmbclientNeighborPlugin.cxx

@@ -17,7 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "config.h"
 #include "SmbclientNeighborPlugin.hxx"
 #include "lib/smbclient/Init.hxx"
 #include "lib/smbclient/Domain.hxx"

src/neighbor/plugins/UdisksNeighborPlugin.cxx

@@ -17,7 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "config.h"
 #include "UdisksNeighborPlugin.hxx"
 #include "lib/dbus/Connection.hxx"
 #include "lib/dbus/Error.hxx"

src/neighbor/plugins/UpnpNeighborPlugin.cxx

@@ -17,7 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#include "config.h"
 #include "UpnpNeighborPlugin.hxx"
 #include "lib/upnp/ClientInit.hxx"
 #include "lib/upnp/Discovery.hxx"