Fix LIBMODBUS_VERSION_HEX encoding (closes stephane#345)

The result of LIBMODBUS_VERSION_HEX is left-shifted by an extra
factor of 8 bits.

For example, current implementation for version 1.2.3 would be
encoded like 0x01020300 instead of 0x010203.

src/modbus-version.h.in

@@ -35,10 +35,10 @@
  */
 #define LIBMODBUS_VERSION_STRING "@LIBMODBUS_VERSION@"
 
-/* Numerically encoded version, like 0x010203 */
-#define LIBMODBUS_VERSION_HEX ((LIBMODBUS_VERSION_MAJOR << 24) |  \
-                               (LIBMODBUS_VERSION_MINOR << 16) |  \
-                               (LIBMODBUS_VERSION_MICRO << 8))
+/* Numerically encoded version, eg. v1.2.3 is 0x010203 */
+#define LIBMODBUS_VERSION_HEX ((LIBMODBUS_VERSION_MAJOR << 16) |  \
+                               (LIBMODBUS_VERSION_MINOR <<  8) |  \
+                               (LIBMODBUS_VERSION_MICRO <<  0))
 
 /* Evaluates to True if the version is greater than @major, @minor and @micro
  */

tests/version.c

@@ -9,7 +9,7 @@
 
 int main(void)
 {
-    printf("Compiled with libmodbus version %s (%08X)\n", LIBMODBUS_VERSION_STRING, LIBMODBUS_VERSION_HEX);
+    printf("Compiled with libmodbus version %s (%06X)\n", LIBMODBUS_VERSION_STRING, LIBMODBUS_VERSION_HEX);
     printf("Linked with libmodbus version %d.%d.%d\n",
            libmodbus_version_major, libmodbus_version_minor, libmodbus_version_micro);