tests: Add script to make LFS for running tests

The NTest tests take a lot of RAM if we just run them there.  So
instead, push them into LFS to give us some more wiggle room.

tests/preflight-lfs.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env zsh
+
+set -e -u
+
+SELFDIR=$(dirname $(readlink -f $0))
+
+LUAFILES=(
+  # Infrastructure
+  ${SELFDIR}/../lua_examples/lfs/_init.lua
+  ${SELFDIR}/../lua_examples/lfs/dummy_strings.lua
+  ${SELFDIR}/../lua_examples/pipeutils.lua # accelerates TCL xfer
+
+  ${SELFDIR}/NTest/NTest.lua
+  ${SELFDIR}/utils/NTestEnv.lua
+  ${SELFDIR}/utils/NTestTapOut.lua
+
+  # Lua modules exercised by test programs
+
+  # Test programs
+  ${SELFDIR}/NTest_*.lua
+)
+
+if [ -e ${SELFDIR}/../luac.cross.int ]; then
+  echo "Found integer Lua cross compiler..."
+  ${SELFDIR}/../luac.cross.int -f -o ${NODEMCU_TESTTMP}/tmp-lfs-int.img   ${LUAFILES[@]}
+  echo " ... and generated ${NODEMCU_TESTTMP}/tmp-lfs-int.img"
+fi
+
+if [ -e ${SELFDIR}/../luac.cross ]; then 
+  echo "Found float Lua cross compiler..."
+  ${SELFDIR}/../luac.cross     -f -o ${NODEMCU_TESTTMP}/tmp-lfs-float.img ${LUAFILES[@]}
+  echo " ... and generated ${NODEMCU_TESTTMP}/tmp-lfs-float.img"
+fi