INSTALL: update information about cross-compilation.

Author: t-w

INSTALL

@@ -174,9 +174,11 @@ Find produced DLL and EXE and copy wherever you want...
 Cross-compilation (an example)
 -------------------------------
 
+1. With CMake:
+
 Building for Windows can be done cross-compiling eg. on Linux with MinGW:
 
-  $ CC=i686-w64-mingw32-gcc util/cmake_shared_configure
+  $ CC=x86_64-w64-mingw32-gcc util/cmake_shared_configure
 
 or just use:
 
@@ -194,6 +196,14 @@ require eg. configuring Windows CMake or tinkering test configuration to use
 Wine for execution etc...
 It should rather be tested and used on the native target system.
 
+2. With autotools:
+
+  $ ./autogen.sh
+  $ mkdir build
+  $ cd build
+  $ ../configure --host=x86_64-w64-mingw32
+  $ make
+
 
 Links
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