Exploded image has _the. files on system module path

We need to change module path implementation to not tolerate unrecognized files in directories on the module path. This requires addressing two issues first:

1. jdk/modules/ contains _the.* marker files from the build.

2. make/CreateJmods.gmk creates the JMOD as a .tmp file before renaming it into place.

We can easily fix #2 to create the JMOD to somewhere under support before renaming it into place. #1 requires build expertise to see what is possible.