Add a few more filename rewrites

Add a few more filename rewrites

This now allows a full pipeline to work, something such as:
yosys -p "synth_ecp5 -json ~/work/fpga/prjtrellis/examples/ecp5_evn/blinky.v"

Otherwise, you will get something along the lines of:
ERROR: Can't open output file `~/work/fpga/prjtrellis/examples/ecp5_evn/blinky.v' for writing: No such file or directory

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>