Meson: Use systemd inspiration for building man pages.

customman = join_paths(meson.current_source_dir(), 'custom-man.xsl')

customhtml = join_paths(meson.current_source_dir(), 'custom-html.xsl')

if xsltproc.found() and get_option('enable-doc')

  customman = files('custom-man.xsl')

  customhtml = files('custom-html.xsl')

man1dir = join_paths(get_option('mandir'), 'man1')

commonargs = [

  xsltproc,

  flags = [

    '--nonet',

    '--xinclude',

    '--stringparam', 'man.output.quietly', '1',

    '--stringparam', 'man.authors.section.enabled', '1',

    '--stringparam',  'man.copyright.section.enabled', '1',

  '--stringparam', 'mlm.version', meson.project_version(),

  '--path', meson.current_source_dir(),

  '-o', '@OUTPUT@'

    '--stringparam', 'mlm.version', '@0@'.format(meson.project_version()),

    '--path', '@0@:@1@'.format(meson.current_build_dir(),

                               meson.current_source_dir())

  ]

genman1 = [ commonargs, customman, '@INPUT@' ]

name = 'analyze'

custom_target('mlm-' + name + '.1',

              output: 'mlm-' + name + '.1',

              input: 'mlm-' + name + '.xml',

              command: genman1, install: true, install_dir: man1dir)

name = 'copy-tags'

custom_target('mlm-' + name + '.1',

              output: 'mlm-' + name + '.1',

              input: 'mlm-' + name + '.xml',

              command: genman1, install: true, install_dir: man1dir)

name = 'tags'

custom_target('mlm-' + name + '.1',

              output: 'mlm-' + name + '.1',

              input: 'mlm-' + name + '.xml',

              command: genman1, install: true, install_dir: man1dir)

  command = [ xsltproc, '-o', '@OUTPUT@' ] + flags

  manpages = [ 'analyze', 'copy-tags', 'tags' ]

  man_pages = []

  html_pages = []

  foreach manpage : manpages

    stem = 'mlm-' + manpage

    xml = stem + '.xml'

    html = stem + '.html'

    man = stem + '.1'

    mandir = join_paths(get_option('mandir'), 'man1')

    htmldir = join_paths(docdir, 'html')

    p1 = custom_target(man,

                       input : xml,

                       output : man,

                       command : command + [ customman, '@INPUT@' ],

                       install : true,

                       install_dir : mandir )

    man_pages += [ p1 ]

    p2 = custom_target(html,

                       input : xml,

                       output : html,

                       command : command + [ customhtml, '@INPUT@' ],

                       install : true,

                       install_dir : htmldir )

    html_pages += [ p2 ]

  endforeach

  man = custom_target('man',

                      output: 'man',

                      depends: man_pages,

                      command: ['echo'])

  html = custom_target('html',

                      output: 'html',

                      depends: html_pages,

                      command: ['echo'])

endif