games-strategy/widelands: Do not depend on dev-lang/lua

Short version: this package builds, tests and installs without any
errors on systems without any versions of Lua installed, and even when a
copy of Lua *is* installed does not interact with it in any way (which
was already reflected by the fact dev-lang/lua was not mentioned in
RDEPEND, only in DEPEND).

Details:

Widelands source code comes bundled with Lua - or to be precise with
Eris (https://github.com/fnuecke/eris), which according to its upstream
should be considered "a custom 'distribution' of Lua" due to the fact it
hooks heavily into Lua internals. Since src/third_party/eris/README.eris
explicitly states that the bundled Eris is what brings in the Lua
version used in Widelands, it is no surprise that upstream build scripts
do not even attempt to look for system Lua.

Bug: https://bugs.gentoo.org/752729
Signed-off-by: Marek Szuba <marecki@gentoo.org>

games-strategy/widelands/widelands-0.20-r1.ebuild

@@ -32,7 +32,6 @@ RDEPEND="
 	sys-libs/zlib:=[minizip]"
 DEPEND="${RDEPEND}
 	${PYTHON_DEPS}
-	dev-lang/lua:0
 "
 BDEPEND="
 	sys-devel/gettext

games-strategy/widelands/widelands-9999.ebuild

@@ -39,7 +39,6 @@ RDEPEND="
 	sys-libs/zlib:=[minizip]"
 DEPEND="${RDEPEND}
 	${PYTHON_DEPS}
-	dev-lang/lua:0
 "
 BDEPEND="
 	sys-devel/gettext