Base Makefile improvements.
Base Makefile improvements.

Instead of calling make in subdirectories using a sh for loop, use GNU
make's $(foreach ) to create a string of commands connected with &&.
This way an error in a subdirectory will stop the build, instead of
continuing on to the next subdirectory, which the old version does.

Also added rules to regenerate configure when configure.in changes,
and to run config.status --recheck when that happens.

CastMi/iverilog,themperek/iverilog,themperek/iverilog,CastMi/iverilog,CastMi/iverilog,themperek/iverilog