openocd: include config.h in every file .c

Including config.h as first is required for every C file.
Add it to the C files that still miss it.

Change-Id: I1a210e7d3a854958a85a290b086ad8a9f5176425
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6856
Tested-by: jenkins

src/server/rtt_server.c

@@ -15,6 +15,10 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include <stdint.h>
 #include <rtt/rtt.h>