Honor system specific paths of MAN pages

[krytarowski]

Summary

Caught on NetBSD.

[beanz]

This looks fine to me, but looping in jroelofs as he wrote the original patch.

[jroelofs]

LGTM

[krytarowski]

Please land it, I'm not a committer.

INSTALL.txt

 // Step 4: Install Clang
 //===----------------------------------------------------------------------===//
 
 From inside the Clang build directory, run 'make install' to install the Clang
 compiler and header files into the prefix directory selected when LLVM was
 configured.
 
 The Clang compiler is available as 'clang' and 'clang++'. It supports a gcc like
-command line interface. See the man page for clang (installed into
-$prefix/share/man/man1) for more information.
+command line interface. See the man page for clang for more information.

tools/scan-build/CMakeLists.txt

 option(CLANG_INSTALL_SCANBUILD "Install the scan-build tool" ON)
 
+include(GNUInstallDirs)
+
 if (WIN32 AND NOT CYGWIN)
   set(BinFiles
         scan-build.bat)
   set(LibexecFiles
         ccc-analyzer.bat
         c++-analyzer.bat)
 else()
   set(BinFiles
add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/libexec/${LibexecFile}
                          ${CMAKE_CURRENT_SOURCE_DIR}/libexec/${LibexecFile}
                          ${CMAKE_BINARY_DIR}/libexec/
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/libexec/${LibexecFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/libexec/${LibexecFile})
     install(PROGRAMS libexec/${LibexecFile} DESTINATION libexec)
   endforeach()
 
   foreach(ManPage ${ManPages})
-    add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/share/man/man1/${ManPage}
+    add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_MANDIR}/man1/${ManPage}
                        COMMAND ${CMAKE_COMMAND} -E make_directory
-                         ${CMAKE_BINARY_DIR}/share/man/man1
+                         ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_MANDIR}/man1
                        COMMAND ${CMAKE_COMMAND} -E copy
                          ${CMAKE_CURRENT_SOURCE_DIR}/man/${ManPage}
-                         ${CMAKE_BINARY_DIR}/share/man/man1/
+                         ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_MANDIR}/man1/
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/man/${ManPage})
-    list(APPEND Depends ${CMAKE_BINARY_DIR}/share/man/man1/${ManPage})
-    install(PROGRAMS man/${ManPage} DESTINATION share/man/man1)
+    list(APPEND Depends ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_MANDIR}/man1/${ManPage})
+    install(PROGRAMS man/${ManPage} DESTINATION ${CMAKE_INSTALL_MANDIR}/man1)
   endforeach()
 
   foreach(ShareFile ${ShareFiles})
     add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/share/scan-build/${ShareFile}
                        COMMAND ${CMAKE_COMMAND} -E make_directory
                          ${CMAKE_BINARY_DIR}/share/scan-build
                        COMMAND ${CMAKE_COMMAND} -E copy
                          ${CMAKE_CURRENT_SOURCE_DIR}/share/scan-build/${ShareFile}
                          ${CMAKE_BINARY_DIR}/share/scan-build/
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/share/scan-build/${ShareFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/share/scan-build/${ShareFile})
     install(FILES share/scan-build/${ShareFile} DESTINATION share/scan-build)
   endforeach()
 
   add_custom_target(scan-build ALL DEPENDS ${Depends})
   set_target_properties(scan-build PROPERTIES FOLDER "Misc")
 endif()
-