mingw32: Build for Windows XP by default. Add note about Win9x/2000 support.

Originally committed as revision 21227 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -2023,6 +2023,8 @@ case $target_os in
             { check_cflags -mdynamic-no-pic && add_asflags -mdynamic-no-pic; }
         ;;
     mingw32*)
+        # Only WinXP or greater are supported
+        add_cflags -D_WIN32_WINNT=0x0501
         if test $target_os = "mingw32ce"; then
             disable network
         else

doc/general.texi

@@ -996,6 +996,13 @@ and for a build with shared libraries
 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
 @end example
 
+@subsection Win9x/Win2000 support
+
+FFmpeg is built by default for Windows XP and above. To run it on any Windows
+version prior to XP, you may have to disable network support. Additionally, for
+Windows 98/Me you must install KernelEx from:
+http://sourceforge.net/projects/kernelex/
+
 @section BeOS
 
 BeOS support is broken in mysterious ways.