xorg-libXaw: Remove groff dependency

groff is not used anymore as of libXaw 1.0.8.

See: https://trac.macports.org/ticket/69601

Also use path dep for pkgconfig, disable silent rules, and suppress
strchr implicit function declaration warning.

x11/xorg-libXaw/Portfile

@@ -23,8 +23,7 @@ distname        libXaw-${version}
 
 use_xz          yes
 
-depends_build   port:pkgconfig \
-                port:groff
+depends_build   path:bin/pkg-config:pkgconfig
 
 depends_lib     port:xorg-libsm \
                 port:xorg-libXext \
@@ -34,7 +33,11 @@ depends_lib     port:xorg-libsm \
 
 patchfiles      patch-src-vendor.diff
 
+# https://trac.macports.org/wiki/WimplicitFunctionDeclaration#strchr
+configure.checks.implicit_function_declaration.whitelist-append strchr
+
 configure.args \
+        --disable-silent-rules \
         --disable-specs \
         --without-xmlto \
         --without-fop