docs: Explain how to regenerate import libraries with MSVC tools

Signed-off-by: Martin Storsjö <martin@martin.st>

doc/general.texi

@@ -970,6 +970,34 @@ required when using import libraries generated by lib.exe.
 This issue is reported upstream at
 @url{http://sourceware.org/bugzilla/show_bug.cgi?id=12633}.
 
+To create import libraries that work with the @code{/OPT:REF} option
+(which is enabled by default in Release mode), follow these steps:
+
+@enumerate
+
+@item Open @file{Visual Studio 2005 Command Prompt}.
+
+Alternatively, in a normal command line prompt, call @file{vcvars32.bat}
+which sets up the environment variables for the Visual C++ tools
+(the standard location for this file is
+@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat}).
+
+@item Enter the @file{bin} directory where the created LIB and DLL files
+are stored.
+
+@item Generate new import libraries with @file{lib.exe}:
+
+@example
+lib /machine:i386 /def:..\lib\avcodec-53.def  /out:avcodec.lib
+lib /machine:i386 /def:..\lib\avdevice-53.def /out:avdevice.lib
+lib /machine:i386 /def:..\lib\avfilter-2.def  /out:avfilter.lib
+lib /machine:i386 /def:..\lib\avformat-53.def /out:avformat.lib
+lib /machine:i386 /def:..\lib\avutil-51.def   /out:avutil.lib
+lib /machine:i386 /def:..\lib\swscale-2.def   /out:swscale.lib
+@end example
+
+@end enumerate
+
 @anchor{Cross compilation for Windows with Linux}
 @subsection Cross compilation for Windows with Linux