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/protocol/Ack.cxx

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

src/protocol/ArgParser.cxx

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

src/protocol/ArgParser.hxx

@@ -20,8 +20,6 @@
 #ifndef MPD_PROTOCOL_ARGPARSER_HXX
 #define MPD_PROTOCOL_ARGPARSER_HXX
 
-#include "check.h"
-
 #include <stdint.h>
 
 struct RangeArg;

src/protocol/RangeArg.hxx

@@ -20,8 +20,6 @@
 #ifndef MPD_PROTOCOL_RANGE_ARG_HXX
 #define MPD_PROTOCOL_RANGE_ARG_HXX
 
-#include "check.h"
-
 #include <limits>
 
 struct RangeArg {

src/protocol/Result.cxx

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

src/protocol/Result.hxx

@@ -20,8 +20,6 @@
 #ifndef MPD_PROTOCOL_RESULT_HXX
 #define MPD_PROTOCOL_RESULT_HXX
 
-#include "check.h"
-
 class Client;
 
 void