Configure: workaround for system perl on OS X (ticket #576).

auto/lib/perl/conf

diff --git a/auto/lib/perl/conf b/auto/lib/perl/conf
index 2fbaa76..91009f1 100644
--- a/auto/lib/perl/conf
+++ b/auto/lib/perl/conf
@@ -52,6 +52,11 @@
         ngx_perl_ldopts=`echo $ngx_perl_ldopts | sed 's/ -pthread//'`
     fi
 
+    if [ "$NGX_SYSTEM" = "Darwin" ]; then
+        # OS X system perl wants to link universal binaries
+        ngx_perl_ldopts=`echo $ngx_perl_ldopts | sed -e 's/-arch x86_64 -arch i386//'`
+    fi
+
     CORE_LINK="$CORE_LINK $ngx_perl_ldopts"
     LINK_DEPS="$LINK_DEPS $NGX_OBJS/src/http/modules/perl/blib/arch/auto/nginx/nginx.$ngx_perl_dlext"