Standardise header guards across codebase ...

All identifiers, regardless of use, that start with two underscores are
reserved. This means they can't be used in header guards.

The style that this project is now to use the full name of the file in
capital letters followed by 'H'. For example, for a file called
"uart_example.h", the header guard is UART_EXAMPLE_H.

The exceptions are files that are imported from other projects:

- CryptoCell driver
- dt-bindings folders
- zlib headers

Change-Id: I50561bf6c88b491ec440d0c8385c74650f3c106e
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

fiptool: Enable Visual Studio build ...

Updates are required to enable the fiptool utility to be built on a
Windows platform.  This change modifies the source files to enable
building with Visual Studio (detected via preprocessor settings).
The primary changes are:
  1.  Provide an implementation of the getopt_long function.  This does
      not exist in the Visual Studio CRT libraries because Windows
      commands normally use '/' not '-' as an option indicator.
  2.  Redirect some function names to match those supported by the
      Visual Studio libraries (when building with Visual Studio).
  2.  Modify a structure name (stat) to match that provided
      by the Visual Studio libraries (_stat).

Note - this change does not provide makefile updates.  It only modifies
       the sources to enable the fiptool to be built from a Visual
       Studio project.  In normal use the presence of FIPTOOL.EXE is
       enough to satisfy the make requirements.  A makefile change may
       be derived from the Visual Studio command line information at
       some point in the future.

Change-Id: I3ade77ea140246af3c030920b3f97c070087f111
Signed-off-by: Evan Lloyd <evan.lloyd@arm.com>