Move stdlib header files to include/lib/stdlib ...

* 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

Make:Allow for extension in tool names. ...

In some build environments executable programs have a specific file
extension.  The value of BIN_EXT is appended to the relevant tool file
names to allow for this.
The value of BIN_EXT is set, where appropriate, by the build environment
specific make helper (to .exe for Windows build environments).

.gitignore is updated to hide the new (.exe) files.

Change-Id: Icc32f64b750e425265075ad4e0dea18129640b86

Make:Use "simply expanded" make variables. ...

Replace some "recursively expanded" make variables with "simply
expanded" variables (i.e. replace = with :=). This has no functional
impact but is more consistent and theoretically more efficient.

Change-Id: Iaf33d7c8ad48464ae0d39923515d1e7f230c95c1

Build:Replace soft links with file copy. ...

Some build environments do not support symbolic links. This patch
removes the symlinks previously used to build fip_create and instead
copies the relevant header files.
The original motivation for using symlinks was to avoid Trusted Firmware
library headers conflicting with headers in the compiler standard
include path. Copying the header files instead has the same effect.

Like other build artefacts, the copied files are listed in .gitignore.

The distclean targets have also been updated to remove the copies.

Change-Id: Ie8b67bcb133f7f1d660ae93b857950aa15e42b1e

Make:Use environment variables for OS detection. ...

Add make helper files to select the appropriate settings for the build
environment. Selection is made in make_helpers/build_env.mk, which
selects other files to include using generic build environment settings.
The Trusted Firmware Makefile and supporting tool Makefiles are updated
to include build_env.mk instead of unix.mk.

NOTE: This change does not fully enable builds in other build
      environments. It facilitates this without compromising the
      existing build environments.

Change-Id: Ic4064ffe6ce158bbd16d7cc9f27dd4655a3580f6

Make:Make shell commands more portable ...

Macros are inserted to replace direct invocations of commands that are
problematic on some build environments. (e.g. Some environments expect
\ in paths instead of /.)
The changes take into account mismatched command mappings across
environments.
The new helper file unix.mk retains existing makefile behaviour on unix
like build environments by providing the following macro definitions:
  SHELL_COPY        cp -f
  SHELL_COPY_TREE   cp -rf
  SHELL_DELETE      rm -f
  SHELL_DELETE_ALL  rm -rf
  MAKE_PREREQ_DIR   mkdir -p  (As make target)
  SHELL_REMOVE_DIR  rm -rf

Change-Id: I1b5ca5e1208e78230b15284c4af00c1c006cffcb

Fix problem of dependencies on the fiptool makefile target ...

The 'fiptool' target doesn't depend on fip_create's source files,
neither directly nor indirectly. As a result, the FIP tool is not
rebuilt whenever its source files change.

This patch makes the ${FIPTOOL} target into a phony target so that the
FIP tool's sub-makefile is always called. The sub-makefile correctly
handles the dependencies. It also moves the completion message into
the sub-makefile so that it is only displayed when the tool is
actually recompiled.

Fixes ARM-software/tf-issues#278

Change-Id: Ia027519fe51d3c42be30665d1ad20a7b89fa350f

Cleanup FIP build targets and messages ...

At present the fip.bin depends on phony targets for BL images, resulting
in unconditional remake of fip.bin. Also the build messages doesn't
match with the rest of build system.

This patch modifies the fip.bin dependencies to the actual BL binary
images so that fip.bin is remade only when the component images are
rebuilt/modified. The build messages and FIP Makefile are modified to
match the style of rest of the build system.

Change-Id: I8dd08666ff766d106820a5b4b037c2161bcf140f

Add Firmware Image Package creation tool ...

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