replace stdint.h with cstdint

The former is deprecated by C++14. The standard says they are the same:

The header defines all types and macros the same as the C standard library
header<stdint.h>.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/db/Count.hxx

@@ -22,7 +22,7 @@
 
 #include "util/Compiler.h"
 
-#include <stdint.h>
+#include <cstdint>
 
 enum TagType : uint8_t;
 struct Partition;

src/db/DatabasePrint.hxx

@@ -20,7 +20,7 @@
 #ifndef MPD_DB_PRINT_H
 #define MPD_DB_PRINT_H
 
-#include <stdint.h>
+#include <cstdint>
 
 template<typename T> struct ConstBuffer;
 enum TagType : uint8_t;

src/db/update/InotifySource.cxx

@@ -26,9 +26,9 @@
 
 #include <cerrno>
 #include <climits>
+#include <cstdint>
 
 #include <sys/inotify.h>
-#include <stdint.h>
 
 bool
 InotifySource::OnSocketReady(gcc_unused unsigned flags) noexcept