games/pioneer: Fix lua build.

Signed-off-by: B. Watson <yalhcru@gmail.com>

Signed-off-by: Willy Sudiarto Raharjo <willysr@slackbuilds.org>

games/pioneer/pioneer.SlackBuild

@@ -81,12 +81,23 @@ GLEW=OFF
 LUA=OFF
 
 pkg-config --exists glew && GLEW=ON
-pkg-config --exists lua5.2 && LUA=ON
+
+# 20210214 bkw: cmake can't easily be told to ignore lua 5.1 on a
+# system where both 5.1 and 5.2 are installed. In that case, we'll
+# use the bundled lua source. Note that there's no problem with 5.3,
+# as cmake seems to search for them in order.
+pkg-config --exists lua5.2 && ! pkg-config --exists lua && LUA=ON
 
 # Workaround 32-bit build failure
 # https://github.com/pioneerspacesim/pioneer/issues/4691
 patch -p1 < $CWD/alignment.patch
 
+# 20210214 bkw: prevent the build from writing to /root/, without
+# breaking ccache if it's in use.
+mkdir -p tmphome
+export CCACHE_DIR=${CCACHE_DIR:-$HOME/.ccache}
+export HOME=$( pwd )/tmphome
+
 mkdir -p build
 cd build
   cmake \