Add toolchain_rule to enable rule authors to define toolchains.

Change-Id: I407240708f4aacc89ec5c00bf3e8ff46a1d6d6d6
PiperOrigin-RevId: 152692981
diff --git a/src/create_embedded_tools.sh b/src/create_embedded_tools.sh
index 9a0eee5..0c510ee 100755
--- a/src/create_embedded_tools.sh
+++ b/src/create_embedded_tools.sh
@@ -42,6 +42,7 @@
   case "$i" in
     *tools/jdk/BUILD*) OUTPUT_PATH=tools/jdk/BUILD ;;
     *tools/platforms/platforms.BUILD) OUTPUT_PATH=platforms/BUILD ;;
+    *tools/platforms/*) OUTPUT_PATH=platforms/${i##*/} ;;
     *JavaBuilder*_deploy.jar) OUTPUT_PATH=tools/jdk/${i##*/} ;;
     *JacocoCoverage*_deploy.jar) OUTPUT_PATH=tools/jdk/JacocoCoverage_deploy.jar ;;
     *turbine_deploy.jar) OUTPUT_PATH=tools/jdk/turbine_deploy.jar ;;