tests: depend on stdlib and new libhexagonrpc header file

Both the hexagonfs and iobuffer tests need malloc and free. The iobuffer
test also needs REMOTE_SCALARS_MAKE. Include stdlib directly and include
the new libhexagonrpc header file.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>

tests/test_hexagonfs.c

@@ -20,8 +20,8 @@
  */
 
 #include <fcntl.h>
-#include <libhexagonrpc/fastrpc.h>
 #include <stdbool.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 

tests/test_iobuffer.c

@@ -19,7 +19,8 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-#include <libhexagonrpc/fastrpc.h>
+#include <libhexagonrpc/hexagonrpc.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "../hexagonrpcd/iobuffer.h"