doc/platform: Update to reflect current MSVC build situation

Also update the C99 converter URL, since it uses GitHub Releases
to host the binaries now.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

doc/platform.texi

@@ -108,14 +108,16 @@ libavformat) as DLLs.
 
 @section Microsoft Visual C++ or Intel C++ Compiler for Windows
 
-FFmpeg can be built with MSVC or ICL using a C99-to-C89 conversion utility and
-wrapper. For ICL, only the wrapper is used, since ICL supports C99.
+FFmpeg can be built with MSVC 2012 or earlier using a C99-to-C89 conversion utility
+and wrapper, or with MSVC 2013 and ICL natively.
 
 You will need the following prerequisites:
 
 @itemize
-@item @uref{http://download.videolan.org/pub/contrib/c99-to-c89/, C99-to-C89 Converter & Wrapper}
+@item @uref{https://github.com/libav/c99-to-c89/, C99-to-C89 Converter & Wrapper}
+(if using MSVC 2012 or earlier)
 @item @uref{http://code.google.com/p/msinttypes/, msinttypes}
+(if using MSVC 2012 or earlier)
 @item @uref{http://www.mingw.org/, MSYS}
 @item @uref{http://yasm.tortall.net/, YASM}
 @item @uref{http://gnuwin32.sourceforge.net/packages/bc.htm, bc for Windows} if
@@ -125,14 +127,16 @@ you want to run @uref{fate.html, FATE}.
 To set up a proper environment in MSYS, you need to run @code{msys.bat} from
 the Visual Studio or Intel Compiler command prompt.
 
-Place @code{makedef}, @code{c99wrap.exe}, @code{c99conv.exe}, and @code{yasm.exe}
-somewhere in your @code{PATH}.
+Place @code{yasm.exe} somewhere in your @code{PATH}. If using MSVC 2012 or
+earlier, place @code{c99wrap.exe} and @code{c99conv.exe} somewhere in your
+@code{PATH} as well.
 
-Next, make sure @code{inttypes.h} and any other headers and libs you want to use
-are located in a spot that the compiler can see. Do so by modifying the @code{LIB}
-and @code{INCLUDE} environment variables to include the @strong{Windows} paths to
-these directories. Alternatively, you can try and use the
-@code{--extra-cflags}/@code{--extra-ldflags} configure options.
+Next, make sure any other headers and libs you want to use, such as zlib, are
+located in a spot that the compiler can see. Do so by modifying the @code{LIB}
+and @code{INCLUDE} environment variables to include the @strong{Windows-style}
+paths to these directories. Alternatively, you can try and use the
+@code{--extra-cflags}/@code{--extra-ldflags} configure options. If using MSVC
+2012 or earlier, place @code{inttypes.h} somewhere the compiler can see too.
 
 Finally, run:
 
@@ -182,7 +186,9 @@ can see.
 @itemize
 @item Visual Studio 2010 Pro and Express
 @item Visual Studio 2012 Pro and Express
+@item Visual Studio 2013 Pro and Express
 @item Intel Composer XE 2013
+@item Intel Composer XE 2013 SP1
 @end itemize
 Anything else is not officially supported.