[LinuxBIOS] shared symbols / initram

[Stefan Reinauer]

Here's the cleaned up version of the XIP/initram patch.

New since the last version:
 * It uses the macro suggestion from Jordan
 * SHARED-ify post_code()
 * use -N during linking initram code to noticably reduce
   initram size (drops ~8k of alignment)
 * rename pci_ops FUNC to DEVFUNC to avoid name clash.