Maintainer: @datafl4sh
Compile tested: x86, sunxi, bcm27xx
Run tested: x86, sunxi, bcm27xx

Description: Updated gnuplot from 5.4.1 to 5.4.2
Signed-off-by: Matteo Cicuttin <datafl4sh@toxicnet.eu>

Note: touches also `libdg`, changed dependency from libjpeg to libjpeg-turbo

Signed-off-by: Matteo Cicuttin <datafl4sh@toxicnet.eu>

Signed-off-by: Matteo Cicuttin <datafl4sh@toxicnet.eu>

Signed-off-by: Matteo Cicuttin <datafl4sh@toxicnet.eu>

About the patch: Gnuplot build process includes the compilation of some
custom binaries which are subsequently used to generate help files/docs.
Since those binaries are compiled for TARGET, this breaks the build on
the HOST. The patch disables the generation of those binaries (and the
documentation).

Signed-off-by: Matteo Cicuttin <datafl4sh@toxicnet.eu>