Revert "Add module 'idmap'."

This reverts commit eb7c4a5e9ed30ccb67ce386922c44abf7f5dc476.
diff --git a/target/product/core.mk b/target/product/core.mk
index 0736502..abb2d9f 100644
--- a/target/product/core.mk
+++ b/target/product/core.mk
@@ -62,7 +62,6 @@
     framework-res \
     hprof-conv \
     icu.dat \
-    idmap \
     installd \
     ip \
     ip-up-vpn \