Use correct tcl syntax to throw exception.
the syntax is "return -code error" not "return -error"
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>
Moves definitions for each layer into their own file, eliminating
layering violations in the built-in TCL code. Updates src/Makefile.am
rules to include all files in the final startup.tcl input file, and
others Makefile.am rules to distribute the new files in our packages.