openposix: generate-makefiles.sh: Change test names.

This commit changes the script that generates openposix Makefiles so
that resulting binaries are prefixed with the directory name, i.e.
1-2.run-test becomes sigaction_1-2.run-test.

Shell (*.sh) testcases are copied in the build process, i.e. 10-1.sh
becomes sigaction_10-1.sh.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>