fix shared libs on MacOSX

based on a patch by İsmail Dönmez

configure

@@ -463,6 +463,9 @@ if [ "$shared" = "yes" ]; then
         echo "SONAME=libx264-$API.dll" >> config.mak
         echo 'IMPLIBNAME=libx264.dll.a' >> config.mak
         echo 'SOFLAGS=-Wl,--out-implib,$(IMPLIBNAME) -Wl,--enable-auto-image-base' >> config.mak
+    elif [ "$SYS" = "MACOSX" ]; then
+        echo "SONAME=libx264.$API.dylib" >> config.mak
+        echo 'SOFLAGS=-dynamiclib -Wl,-single_module -Wl,-read_only_relocs,suppress' >> config.mak        
     else
         echo "SONAME=libx264.so.$API" >> config.mak
         echo 'SOFLAGS=-Wl,-soname,$(SONAME)' >> config.mak