libdv: disable asm for all darwin x86 builds

Closes: https://trac.macports.org/ticket/72206

multimedia/libdv/Portfile

@@ -8,7 +8,6 @@ revision            1
 categories          multimedia
 license             LGPL-2.1+
 maintainers         nomaintainer
-platforms           darwin
 
 description         Quasar DV codec (libdv): software codec for DV video encoding format
 long_description    The Quasar DV codec (libdv) is a software codec for DV video, the \
@@ -30,7 +29,7 @@ patchfiles          libdv-1.0.0-darwin.patch
 
 configure.args      --mandir=${prefix}/share/man   --disable-gtktest --disable-gtk --disable-sdltest
 
-platform darwin i386 {
+if {${os.platform} eq "darwin" && ${configure.build_arch} in {i386 x86_64}} {
     configure.args-append   --disable-asm
 }