Fix two compiler warnings on MinGW/MSYS2.

Fix two compiler warnings on MinGW/MSYS2.

The config.h file must always be included as first file.

  src/output/csv.c: In function 'gen_header':
  src/output/csv.c:64:20: warning: format '%u' expects argument of type 'unsigned int', but argument 3 has type 'uint64_t {aka long long unsigned int}' [-Wformat=]
   #define LOG_PREFIX "output/csv"
                      ^
  ./src/libsigrok-internal.h:753:42: note: in expansion of macro 'LOG_PREFIX'
   #define sr_info(...) sr_log(SR_LOG_INFO, LOG_PREFIX ": " __VA_ARGS__)
                                            ^
  src/output/csv.c:244:3: note: in expansion of macro 'sr_info'
     sr_info("Set sample period to %" PRIu64 " %s",
     ^
  src/output/csv.c: In function 'dump_saved_values':
  src/output/csv.c:462:34: warning: format '%u' expects argument of type 'unsigned int', but argument 3 has type 'uint64_t {aka long long unsigned int}' [-Wformat=]
       g_string_append_printf(*out, "%" PRIu64 "%s",
                                    ^

  In file included from src/hardware/ftdi-la/protocol.c:21:0:
  src/hardware/ftdi-la/protocol.c: In function 'send_samples':
  src/hardware/ftdi-la/protocol.h:28:20: warning: format '%u' expects argument of type 'unsigned int', but argument 3 has type 'uint64_t {aka long long unsigned int}' [-Wformat=]
   #define LOG_PREFIX "ftdi-la"
                      ^
  ./src/libsigrok-internal.h:751:42: note: in expansion of macro 'LOG_PREFIX'
   #define sr_spew(...) sr_log(SR_LOG_SPEW, LOG_PREFIX ": " __VA_ARGS__)
                                            ^
  src/hardware/ftdi-la/protocol.c:29:2: note: in expansion of macro 'sr_spew'
    sr_spew("Sending %" PRIu64 " samples.", samples_to_send);
    ^