Respect FHS for manpages

[ajakk]

According the the FHS, manpages go in /usr/share/man: https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s11.html#usrsharemanManualPages

But sshping currently installs its manpage to ${CMAKE_INSTALL_PREFIX}/man. One could Set CMAKE_INSTALL_PREFIX to /usr/share, but then one would get the sshping binary in /usr/share, which isn't really desirable. The AUR package, for example, does indeed install to /usr/share:

https://aur.archlinux.org/cgit/aur.git/tree/PKGBUILD?h=sshping#n28

And I already have this patch for the ebuild in my overlay:

https://gitlab.com/ajak/ajak/-/blob/master/net-analyzer/sshping/files/sshping-0.1.4-fix-man-dir.patch

Signed-off-by: John Helmert III [email protected]