move per-OS build scripts out of travis folder

.github/actions/linux-install.sh

@@ -0,0 +1,32 @@
+export gampath="dist/gam"
+rm -rf $gampath
+mkdir -p $gampath
+export gampath=$(readlink -e $gampath)
+$python -OO -m PyInstaller --clean --noupx --strip -F --distpath $gampath gam.spec
+export gam="${gampath}/gam"
+export GAMVERSION=`$gam version simple`
+cp LICENSE $gampath
+cp GamCommands.txt $gampath
+this_glibc_ver=$(ldd --version | awk '/ldd/{print $NF}')
+GAM_ARCHIVE="gam-${GAMVERSION}-${GAMOS}-${PLATFORM}-glibc${this_glibc_ver}.tar.xz"
+rm $gampath/lastupdatecheck.txt
+# tar will cd to dist and tar up gam/
+tar -C dist/ --create --file $GAM_ARCHIVE --xz gam
+echo "PyInstaller GAM info:"
+du -h $gam
+time $gam version extended
+if ([ "${ImageOS}" == "ubuntu16" ]) && [ "${HOSTTYPE}" == "x86_64" ]; then
+  GAM_LEGACY_ARCHIVE=gam-${GAMVERSION}-${GAMOS}-${PLATFORM}-legacy.tar.xz
+  $python -OO -m staticx -l /lib/x86_64-linux-gnu/libresolv.so.2 -l /lib/x86_64-linux-gnu/libnss_dns.so.2 $gam $gam-staticx
+  strip $gam-staticx
+  rm $gampath/gam
+  mv $gam-staticx $gam
+  chmod 755 $gam
+  rm $gampath/lastupdatecheck.txt
+  tar -C dist/ --create --file $GAM_LEGACY_ARCHIVE --xz gam
+  echo "Legacy StaticX GAM info:"
+  du -h $gam
+  time $gam version extended
+fi
+echo "GAM packages:"
+ls -l gam-*.tar.xz