Make int32_t available on all systems

Use AC_TYPE_INT32_T and include inttypes.h (if it exists) instead of
stdint.h for maximum portability.

configure.ac

@@ -15,6 +15,7 @@ AC_PROG_LIBTOOL
 # Checks for header files.
 
 # Checks for typedefs, structures, and compiler characteristics.
+AC_TYPE_INT32_T
 
 # Checks for library functions.
 

src/dump.c

@@ -9,7 +9,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <stdint.h>
 #include <assert.h>
 
 #include <jansson.h>

src/load.c

@@ -14,7 +14,6 @@
 #include <string.h>
 #include <stdarg.h>
 #include <assert.h>
-#include <stdint.h>
 
 #include <jansson.h>
 #include "jansson_private.h"

src/utf.h

@@ -8,6 +8,15 @@
 #ifndef UTF_H
 #define UTF_H
 
+#include <config.h>
+
+#ifdef HAVE_INTTYPES_H
+/* inttypes.h includes stdint.h in a standard environment, so there's
+no need to include stdint.h separately. If inttypes.h doesn't define
+int32_t, it's defined in config.h. */
+#include <inttypes.h>
+#endif
+
 int utf8_encode(int codepoint, char *buffer, int *size);
 
 int utf8_check_first(char byte);