Configure: improved workaround for system perl on OS X.

The workaround from baf2816d556d stopped to work because the order of
"-arch x86_64" and "-arch i386" has changed.

auto/lib/perl/conf

diff --git a/auto/lib/perl/conf b/auto/lib/perl/conf
index 2a1a3fe..4d1bcf1 100644
--- a/auto/lib/perl/conf
+++ b/auto/lib/perl/conf
@@ -57,7 +57,7 @@
     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//'`
+                         | sed -e 's/-arch i386//' -e 's/-arch x86_64//'`
     fi
 
     CORE_LINK="$CORE_LINK $ngx_perl_ldopts"