Migrate non-starsha users of <starsha/runner.h> to <base/subprocess.h>
starsha: Make PrintCmds be cleanly passed through

Changes the PrintCmds flag to be a parameter rather than a global.
Removes the excess definitions of the global (And some needless includes)
Make bootstrap make things even faster
Convert starsha to use <base/subprocess>

 - base/subprocess: Add transferring ownership the IO fds
 - strm/: Make it possible to try reading data, rather than forcing a
   handling of PastEndError.
 - update bootstrap.sh for new changes
Reformat / cleanup bootstrap.sh a little

 - To specify a prefix for make install do 'make install PREFIX=/usr/local'
 - Wrap sources at 120 columns (Makes it easier to read the lines)
Remove <starsha/dummy>

It's no longer used. Previously it was used for testing the runner