[dev] Add offsets for class code components.
[app][pcitests] Add class code to bus dump.
[dev] Add basic framebuffer device class.
[dev] Add C++ guards to headers.
[malloc] Add include of stddef.h for required types.
[include] Add a basic errno for third party libs that will need it.
[lib] Add lwip library.

Add a clean version of the lwip distro without any platform config or integration code.
[dev] Add netif class API.
[lib][lwip] Add arch/sys support for LK to LWIP.
[lib][lwip] Add simple network test command base.
[platform][pc] Add PCNET driver to PC platform.
[target][pc-x86] Configure and init PCNET device.
[lib][lwip] Fix make rules to use new GLOBAL_INCLUDES.