GNUInstallDirs: Update CMAKE_INSTALL_MANDIR for FreeBSD

FreeBSD has switched from PREFIX/man ro PREFIX/share/man
see https://cgit.freebsd.org/ports/tree/CHANGES entry 20200115.

Fixes: #22883

Modules/GNUInstallDirs.cmake

@@ -330,7 +330,7 @@ else()
     "Info documentation (DATAROOTDIR/info)")
 endif()
 
-if(CMAKE_SYSTEM_NAME MATCHES "^(([^k].*)?BSD|DragonFly)$")
+if(CMAKE_SYSTEM_NAME MATCHES "^(([^k].*)?BSD|DragonFly)$" AND NOT CMAKE_SYSTEM_NAME MATCHES "^(FreeBSD)$")
   _GNUInstallDirs_cache_path_fallback(CMAKE_INSTALL_MANDIR "man"
     "Man documentation (man)")
 else()

Tests/RunCMake/GNUInstallDirs/Opt-FreeBSD-stderr.txt

@@ -9,7 +9,7 @@ CMAKE_INSTALL_LIBEXECDIR='libexec'
 CMAKE_INSTALL_LOCALEDIR='share/locale'
 CMAKE_INSTALL_LOCALSTATEDIR='var'
 CMAKE_INSTALL_RUNSTATEDIR='var/run'
-CMAKE_INSTALL_MANDIR='man'
+CMAKE_INSTALL_MANDIR='share/man'
 CMAKE_INSTALL_SBINDIR='sbin'
 CMAKE_INSTALL_SHAREDSTATEDIR='com'
 CMAKE_INSTALL_SYSCONFDIR='etc'
@@ -24,7 +24,7 @@ CMAKE_INSTALL_FULL_LIBEXECDIR='/opt/Opt/libexec'
 CMAKE_INSTALL_FULL_LOCALEDIR='/opt/Opt/share/locale'
 CMAKE_INSTALL_FULL_LOCALSTATEDIR='/var/opt/Opt'
 CMAKE_INSTALL_FULL_RUNSTATEDIR='/var/run/opt/Opt'
-CMAKE_INSTALL_FULL_MANDIR='/opt/Opt/man'
+CMAKE_INSTALL_FULL_MANDIR='/opt/Opt/share/man'
 CMAKE_INSTALL_FULL_SBINDIR='/opt/Opt/sbin'
 CMAKE_INSTALL_FULL_SHAREDSTATEDIR='/opt/Opt/com'
 CMAKE_INSTALL_FULL_SYSCONFDIR='/etc/opt/Opt'$

Tests/RunCMake/GNUInstallDirs/Root-FreeBSD-stderr.txt

@@ -9,7 +9,7 @@ CMAKE_INSTALL_LIBEXECDIR='usr/libexec'
 CMAKE_INSTALL_LOCALEDIR='usr/share/locale'
 CMAKE_INSTALL_LOCALSTATEDIR='var'
 CMAKE_INSTALL_RUNSTATEDIR='var/run'
-CMAKE_INSTALL_MANDIR='usr/man'
+CMAKE_INSTALL_MANDIR='usr/share/man'
 CMAKE_INSTALL_SBINDIR='usr/sbin'
 CMAKE_INSTALL_SHAREDSTATEDIR='usr/com'
 CMAKE_INSTALL_SYSCONFDIR='etc'
@@ -24,7 +24,7 @@ CMAKE_INSTALL_FULL_LIBEXECDIR='/usr/libexec'
 CMAKE_INSTALL_FULL_LOCALEDIR='/usr/share/locale'
 CMAKE_INSTALL_FULL_LOCALSTATEDIR='/var'
 CMAKE_INSTALL_FULL_RUNSTATEDIR='/var/run'
-CMAKE_INSTALL_FULL_MANDIR='/usr/man'
+CMAKE_INSTALL_FULL_MANDIR='/usr/share/man'
 CMAKE_INSTALL_FULL_SBINDIR='/usr/sbin'
 CMAKE_INSTALL_FULL_SHAREDSTATEDIR='/usr/com'
 CMAKE_INSTALL_FULL_SYSCONFDIR='/etc'$

Tests/RunCMake/GNUInstallDirs/Usr-FreeBSD-stderr.txt

@@ -9,7 +9,7 @@ CMAKE_INSTALL_LIBEXECDIR='libexec'
 CMAKE_INSTALL_LOCALEDIR='share/locale'
 CMAKE_INSTALL_LOCALSTATEDIR='var'
 CMAKE_INSTALL_RUNSTATEDIR='var/run'
-CMAKE_INSTALL_MANDIR='man'
+CMAKE_INSTALL_MANDIR='share/man'
 CMAKE_INSTALL_SBINDIR='sbin'
 CMAKE_INSTALL_SHAREDSTATEDIR='com'
 CMAKE_INSTALL_SYSCONFDIR='etc'
@@ -24,7 +24,7 @@ CMAKE_INSTALL_FULL_LIBEXECDIR='/usr/libexec'
 CMAKE_INSTALL_FULL_LOCALEDIR='/usr/share/locale'
 CMAKE_INSTALL_FULL_LOCALSTATEDIR='/var'
 CMAKE_INSTALL_FULL_RUNSTATEDIR='/var/run'
-CMAKE_INSTALL_FULL_MANDIR='/usr/man'
+CMAKE_INSTALL_FULL_MANDIR='/usr/share/man'
 CMAKE_INSTALL_FULL_SBINDIR='/usr/sbin'
 CMAKE_INSTALL_FULL_SHAREDSTATEDIR='/usr/com'
 CMAKE_INSTALL_FULL_SYSCONFDIR='/etc'$

Tests/RunCMake/GNUInstallDirs/UsrLocal-FreeBSD-stderr.txt

@@ -9,7 +9,7 @@ CMAKE_INSTALL_LIBEXECDIR='libexec'
 CMAKE_INSTALL_LOCALEDIR='share/locale'
 CMAKE_INSTALL_LOCALSTATEDIR='var'
 CMAKE_INSTALL_RUNSTATEDIR='var/run'
-CMAKE_INSTALL_MANDIR='man'
+CMAKE_INSTALL_MANDIR='share/man'
 CMAKE_INSTALL_SBINDIR='sbin'
 CMAKE_INSTALL_SHAREDSTATEDIR='com'
 CMAKE_INSTALL_SYSCONFDIR='etc'
@@ -24,7 +24,7 @@ CMAKE_INSTALL_FULL_LIBEXECDIR='/usr/local/libexec'
 CMAKE_INSTALL_FULL_LOCALEDIR='/usr/local/share/locale'
 CMAKE_INSTALL_FULL_LOCALSTATEDIR='/usr/local/var'
 CMAKE_INSTALL_FULL_RUNSTATEDIR='/usr/local/var/run'
-CMAKE_INSTALL_FULL_MANDIR='/usr/local/man'
+CMAKE_INSTALL_FULL_MANDIR='/usr/local/share/man'
 CMAKE_INSTALL_FULL_SBINDIR='/usr/local/sbin'
 CMAKE_INSTALL_FULL_SHAREDSTATEDIR='/usr/local/com'
 CMAKE_INSTALL_FULL_SYSCONFDIR='/usr/local/etc'$