Also fix the license information: in older versions the test programs
were GPL 3 licensed, but meanwhile it changed to BSD license.
But since this package only packages the library itself, we can
safely focus only on the LGPL here which covers the library itself.

While at, fix a minor nitpick during library symlink installation.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

Import two patches from upstream in order to fix Modbus-RTU over RS485:
 1c5d969 Only set SER_RS485_ENABLED bit of existing RS485 settings
 91a1d74 Oops fix OR on RS485 settings (1c5d969)

Signed-off-by: Daniel Golle <daniel@makrotopia.org>