Move from inttypes.h to stdint.h

Some toolchains do not have inttypes.h, and we only need stdint.h which is a
subset of it.
diff --git a/library/net.c b/library/net.c
index e6dd5db..8dd4c09 100644
--- a/library/net.c
+++ b/library/net.c
@@ -83,7 +83,7 @@
 #include <basetsd.h>
 typedef UINT32 uint32_t;
 #else
-#include <inttypes.h>
+#include <stdint.h>
 #endif
 
 #if defined(MBEDTLS_PLATFORM_C)