Fix universal architecture compilation of myth on mac.

Following 456083c, found that qmake handle compilation arguments differently according to them being between quotes or not

[cherry-picked from e34c8d7]

Author: jyavenard

mythtv/configure

@@ -4766,7 +4766,7 @@ EOF
 
 # Should be done on all platforms, but for the time being limit it to mac only
 if enabled darwin; then
-  echo "QMAKE_LFLAGS+=$LDFLAGS" >> $TMPMAK
+  echo "QMAKE_LFLAGS+=\"$LDFLAGS\"" >> $TMPMAK
 fi
 
 cp_if_changed $TMPH $MYTH_CONFIG_H