Fix XMPUtils::ConvertToInt64 sscanf() type

This function uses sscanf() with "%lld" or "%llx" to
parse a string to an integer. However, nothing guarantees
that sizeof(XMP_Int64) == sizeof(long long); the latter
is what sscanf will fill with either of these format strings,
to avoid memory corruption.

Use a long long to match the sscanf size, and let the return statement
cast it to XMP_Int64.

xmpsdk/src/XMPUtils.cpp

@@ -1215,7 +1215,7 @@ XMPUtils::ConvertToInt64 ( XMP_StringPtr strValue )
 
 	int count;
 	char nextCh;
-	XMP_Int64 result;
+	long long result;
 
 	if ( ! XMP_LitNMatch ( strValue, "0x", 2 ) ) {
 		count = sscanf ( strValue, "%lld%c", &result, &nextCh );