Use $PROGRAM rather than $CPROTO in test scripts. In early 2016, cproto started consistently failing to build in the Debian Reproducible Builds environment. The cause of the failure was a difference in the output in the test cases. All test cases worked as expected in the first build, but included extra text (the full path to the cproto program as a leading comment) in the second build. . I traced this back to the $CPROTO environment variable. The test scripts use this variable to identify the path to the cproto program on disk, but $CPROTO is also a special variable in cproto itself, intended to hold program arguments. (See the manpage for details.) I'm not sure what in the second build triggered this change in output, but it is clear that $CPROTO is not a safe variable name for this purpose. This patch changes the test scripts to use $PROGRAM rather than $CPROTO. ===================================================================
