Kconfig: Show include paths in menuconfig and documentation

Update Kconfiglib and menuconfig to upstream revision a28bc4da9762e,
which adds include path information to menuconfig, showing how the
Kconfig file of the symbol got 'source'd in addition to showing the
definition location.

Add include path information to the auto-generated Kconfig documentation
too.

Some small Kconfiglib bugs are fixed to, like error reporting for
recursive 'source's being broken (crashing instead of printing the
error), a minor file descriptor leak, and syntax checking not catching
extra trailing tokens after 'if <expr>' and 'depends on <expr>'.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>