libbind: Add groff dependency for tbl on macOS >= 13

Closes: https://trac.macports.org/ticket/69134

Also modernize checksums.

net/libbind/Portfile

@@ -4,8 +4,12 @@ PortSystem 1.0
 
 name                libbind
 version             6.0
+revision            0
+checksums           rmd160  bfafac89a455a05202763f6e10f292978085d811 \
+                    sha256  b98b6aa6e7c403f5a6522ffb68325785a87ea8b13377ada8ba87953a3e8cb29d \
+                    size    757162
+
 categories          net
-platforms           darwin
 maintainers         nomaintainer
 license             ISC
 
@@ -22,5 +26,4 @@ long_description    The libbind functions have been separated from the \
 homepage            http://www.isc.org/software/libbind/60
 master_sites        ftp://ftp.isc.org/isc/libbind/${version}/
 
-checksums           sha1 4664646238cd3602df168da1e9bc9591d3f566b2    \
-                    rmd160 bfafac89a455a05202763f6e10f292978085d811
+depends_build       bin:tbl:groff