"malloc returned something that is in RVM address space" on Mac OS X Lion

Mac OS X Lion runs a 64-bit kernel by default, and introduced changes to gcc to deal with Address Space Layout Randomisation. By default, gcc on 64-bit Lion builds "position independent executables". This appears to cause a bunch of "malloc returned something that is in RVM address space" warnings when running on that configuration. The attached patch fixes this by building with the position independent executable setting turned off on x86_64-osx. This was the default setting for gcc on Mac OS X before Lion.