textmate2: use boost PortGroup

See: https://trac.macports.org/ticket/63136

editors/textmate2/Portfile

@@ -2,12 +2,13 @@
 
 PortSystem              1.0
 PortGroup               github 1.0
+PortGroup               boost 1.0
 
 epoch                   5
 github.setup            textmate textmate 2.0.23 v
 # Change github.tarball_from to 'releases' or 'archive' next update
 github.tarball_from     tarball
-revision                4
+revision                5
 
 maintainers             {cal @neverpanic} openmaintainer
 name                    textmate2
@@ -30,9 +31,10 @@ post-fetch {
     system -W ${worksrcpath} "${git.cmd} submodule update --init"
 }
 
+boost.depends_type      build
+
 depends_build-append    path:lib/libssl.dylib:openssl \
                         path:share/curl/curl-ca-bundle.crt:curl-ca-bundle \
-                        port:boost \
                         port:multimarkdown \
                         port:ninja \
                         port:proctools \