Fix uintN types on Haiku after hrev57738. [skip ci]

In Haiku <SupportDefs.h> defines int8, int16 and int32; other Haiku
headers used to include <SupportDefs.h> implicitly, but this is not the
case since commit 1834e1256:

./rpcap-protocol.h:145:9: error: unknown type name 'uint8'
./rpcap-protocol.h:146:9: error: unknown type name 'uint8'
./rpcap-protocol.h:147:9: error: unknown type name 'uint16'
./rpcap-protocol.h:148:9: error: unknown type name 'uint32'
(and so on)

In rpcap-protocol.h include the header explicitly on Haiku.

rpcap-protocol.h

@@ -137,6 +137,8 @@ typedef unsigned char uint8;	/* 8-bit unsigned integer */
 typedef unsigned short uint16;	/* 16-bit unsigned integer */
 typedef unsigned int uint32;	/* 32-bit unsigned integer */
 typedef int int32;		/* 32-bit signed integer */
+#else
+#include <os/support/SupportDefs.h>
 #endif
 
 /* Common header for all the RPCAP messages */