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* Move stdlib header files from include/stdlib to include/lib/stdlib for
  consistency with other library headers.
* Fix checkpatch paths to continue excluding stdlib files.
* Create stdlib.mk to define the stdlib source files and include directories.
* Include stdlib.mk from the top level Makefile.
* Update stdlib header path in the fip_create Makefile.
* Update porting-guide.md with the new paths.

Change-Id: Ia92c2dc572e9efb54a783e306b5ceb2ce24d27fa

This tool can be used to create a Firmware Image Packages (FIP). These
FIPs store a combined set of firmware images with a Table of Contents
(ToC) that can be loaded by the firmware from platform storage.

- Add uuid.h from FreeBSD.
- Use symbolic links to shared headers otherwise unwanted headers and
  definitions are pulled in.
- A FIP is created as part of the default FVP build.
- A BL3-3 image(e.g. UEFI) must be provided.

Change-Id: Ib73feee181df2dba68bf6abec115a83cfa5e26cb

- This change is split into two separate patches in order to
  simplify the history as interpreted by 'git'. The split is
  between the move/rename and addition of new files.
- Remove dependency on toolchain C library headers and functions in
  order to ensure behavioural compatibility between toolchains.
- Use FreeBSD as reference for C library implementation.
- Do not let GCC use default library include paths.
- Remove unused definitions in modified headers and implementations.
- Move C library files to 'lib/stdlib' and 'include/stdlib'.
- Break std.c functions out into separate files.

Change-Id: I3e3d8d992052264d2a02489034ae4c03bf0f5512