Fix manpage installation when GZ_CLI_EXECUTABLE_NAME is used

[j-rivero]

🦟 Bug fix

Summary

The install steps is failing when GZ_CLI_EXECUTABLE_NAME is being used in the step to install the man files. This happens after #3368.

-- Installing: /home/jenkins/workspace/gazebo11-debbuilder/build/gazebo/debian/tmp/usr/bin/gz11
-- Set runtime path of "/home/jenkins/workspace/gazebo11-debbuilder/build/gazebo/debian/tmp/usr/bin/gz11-11.15.0" to ""
CMake Error at tools/cmake_install.cmake:74 (file):
  file INSTALL cannot find
  "/home/jenkins/workspace/gazebo11-debbuilder/build/gazebo/obj-x86_64-linux-gnu/tools/gz11.1.gz":
  No such file or directory.
Call Stack (most recent call first):
  cmake_install.cmake:103 (include)


make[1]: *** [Makefile:100: install] Error 1

The PR implements modifies slightly the roffman macro to support a third optional parameter that defines a different generated name. That parameter is being used when GZ_CLI_EXECUTABLE_NAME is defined.

Tested with GZ_CLI_EXECUTABLE_NAME in .

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[scpeters]

homebrew build fixed in #3373