doc: Update mingw cross compile instructions

The "Cross compilation for Windows with Linux" section of qemu-doc.texi
still instructs the user to use 'configure --enable-mingw32'
even after the option was removed in Aug 2008:
http://git.savannah.gnu.org/cgit/qemu.git/commit/?id=cd01b4a312248dd4e12c3d389d1a349cea4015d8

This documentation only change updates the instructions to:
* Remove use of '--enable-mingw32' in the configure example
* Correct the 'sdl-config' script name
* Remove references to i386-mingw32msvc.tar.gz which no longer exists in
  recent SDL releases
* Document the zlib dependency

Signed-off-by: Scott Tsai <scottt.tw@gmail.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

qemu-doc.texi

@@ -2313,11 +2313,14 @@ instructions in the download section and the FAQ.
 @item Download
 the MinGW development library of SDL 1.2.x
 (@file{SDL-devel-1.2.x-@/mingw32.tar.gz}) from
-@url{http://www.libsdl.org}. Unpack it in a temporary place, and
+@url{http://www.libsdl.org}. Unpack it in a temporary place and
-unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
+edit the @file{sdl-config} script so that it gives the
-directory. Edit the @file{sdl-config} script so that it gives the
 correct SDL directory when invoked.
 
+@item Install the MinGW version of zlib and make sure
+@file{zlib.h} and @file{libz.dll.a} are in
+MingGW's default header and linker search paths.
+
 @item Extract the current version of QEMU.
 
 @item Start the MSYS shell (file @file{msys.bat}).
@@ -2340,29 +2343,43 @@ correct SDL directory when invoked.
 Install the MinGW cross compilation tools available at
 @url{http://www.mingw.org/}.
 
-@item
+@item Download
-Install the Win32 version of SDL (@url{http://www.libsdl.org}) by
+the MinGW development library of SDL 1.2.x
-unpacking @file{i386-mingw32msvc.tar.gz}. Set up the PATH environment
+(@file{SDL-devel-1.2.x-@/mingw32.tar.gz}) from
-variable so that @file{i386-mingw32msvc-sdl-config} can be launched by
+@url{http://www.libsdl.org}. Unpack it in a temporary place and
+edit the @file{sdl-config} script so that it gives the
+correct SDL directory when invoked.  Set up the @code{PATH} environment
+variable so that @file{sdl-config} can be launched by
 the QEMU configuration script.
 
+@item Install the MinGW version of zlib and make sure
+@file{zlib.h} and @file{libz.dll.a} are in
+MingGW's default header and linker search paths.
+
 @item
 Configure QEMU for Windows cross compilation:
 @example
-./configure --enable-mingw32
+PATH=/usr/i686-pc-mingw32/sys-root/mingw/bin:$PATH ./configure --cross-prefix='i686-pc-mingw32-'
 @end example
-If necessary, you can change the cross-prefix according to the prefix
+The example assumes @file{sdl-config} is installed under @file{/usr/i686-pc-mingw32/sys-root/mingw/bin} and
-chosen for the MinGW tools with --cross-prefix. You can also use
+MinGW cross compilation tools have names like @file{i686-pc-mingw32-gcc} and @file{i686-pc-mingw32-strip}.
---prefix to set the Win32 install path.
+We set the @code{PATH} environment variable to ensure the MingW version of @file{sdl-config} is used and
+use --cross-prefix to specify the name of the cross compiler.
+You can also use --prefix to set the Win32 install path which defaults to @file{c:/Program Files/Qemu}.
+
+Under Fedora Linux, you can run:
+@example
+yum -y install mingw32-gcc mingw32-SDL mingw32-zlib
+@end example
+to get a suitable cross compilation environment.
 
 @item You can install QEMU in the installation directory by typing
-@file{make install}. Don't forget to copy @file{SDL.dll} in the
+@code{make install}. Don't forget to copy @file{SDL.dll} and @file{zlib1.dll} into the
 installation directory.
 
 @end itemize
 
-Note: Currently, Wine does not seem able to launch
+Wine can be used to launch the resulting qemu.exe compiled for Win32.
-QEMU for Win32.
 
 @node Mac OS X
 @section Mac OS X