add simple emscripten dist-script

dist-scripts/emscripten-cores.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+if [ -z "$EMSCRIPTEN" ] ; then
+   echo "run this script with emmake. Ex: emmake $0"
+   exit 1
+fi
+
+make -C ../ -f Makefile.emscripten clean || exit 1
+
+for f in *_emscripten.bc ; do
+   name=`echo "$f" | sed 's/\(_libretro\|\)_emscripten.bc$//'`
+   lto=1
+   echo "building $name"
+   if [ $name = "tyrquake" ] ; then
+      lto=0
+   fi
+   cp -f "$f" ../libretro_emscripten.bc
+   make -C ../ -f Makefile.emscripten LTO=$lto -j7 || exit 1
+   mv -f ../retroarch.js ../emscripten/$name.js
+   rm -f ../retroarch.js
+done