apertium: update to 3.9.4

* Change source from SourceForge to GitHub
* Update to version 3.9.4
* Require C++17
* Link legacysupport / MacPorts libc++ on Darwin < 19
  (for std::filesystem)
* Build using autoreconf

textproc/apertium/Portfile

@@ -1,13 +1,13 @@
 # -*- coding: utf-8; mode: tcl; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- vim:fenc=utf-8:ft=tcl:et:sw=4:ts=4:sts=4
 
 PortSystem              1.0
+PortGroup               github 1.0
+PortGroup               legacysupport 1.1
 
-name                    apertium
-version                 3.4.0
-set branch              [join [lrange [split ${version} .] 0 1] .]
+github.setup            apertium apertium 3.9.4 v
+revision                0
 categories              textproc
 license                 GPL-2+
-platforms               darwin
 maintainers             mm.st:unhammer+dill openmaintainer
 
 description             machine translation platform
@@ -25,12 +25,29 @@ long_description        Apertium is a free and open source machine \
                         new language pairs.
 
 homepage                http://apertium.org/
-master_sites            sourceforge:project/${name}/${name}/${branch}
 
-checksums               rmd160  a5bf6c017cfad361b51fa1fb22a1d59f38cba274 \
-                        sha256  2bd7f44b794615ebca1c5d3949b2139b665e2a5af24c40931ea0856e268fc3da
+checksums               rmd160  40325e2567d5d8af92c434f2d11558fdd44e87e6 \
+                        sha256  b78bf0c36e479c58e31ec10ebe30a031bf876d70ada1e61f52e320a1aa87c4dd \
+                        size    754947
 
-depends_build           port:pkgconfig
+compiler.cxx_standard   2017
+configure.cxxflags-append \
+                        -std=c++17 \
+                        -I${prefix}/include/utf8cpp \
+                        -Wno-register
 
-depends_lib             port:gawk port:libxslt \
+# For std::filesystem
+legacysupport.newest_darwin_requires_legacy 18
+legacysupport.use_mp_libcxx yes
+
+use_autoreconf          yes
+
+depends_build-append    port:autoconf \
+                        port:automake \
+                        port:libtool \
+                        path:bin/pkg-config:pkgconfig \
+                        port:utfcpp
+
+depends_lib-append      port:gawk port:libxslt \
                         port:lttoolbox port:pcre
+