BUILD.Windows: Add documentation to handle the libtool change.

With the recent change to libtool, the default behavior is to use
MinGW's 'ld'. Set the LD variable to direct it to Visual Studio's
linker.

The wordings for the documentation is copied from INSTALL.

Signed-off-by: Gurucharan Shetty <[email protected]>

BUILD.Windows

@@ -37,6 +37,20 @@ Visual studio's linker is used.
 * Get the Open vSwitch sources from either cloning the repo using git
 or from a distribution tar ball.
 
-* Run ./boot.sh; ./configure CC=./build-aux/cccl; make
-(cccl is a wrapper script that provides the right options to Visual c++
-'cl' compiler.)
+* If you pulled the sources directly from an Open vSwitch Git tree,
+  run boot.sh in the top source directory:
+
+  % ./boot.sh
+
+* In the top source directory, configure the package by running the
+  configure script.  You should provide some configure options to choose
+  the right compiler, linker, libraries, Open vSwitch component installation
+  directories, etc. For example,
+
+  % ./configure CC=./build-aux/cccl LD="`which link`" LIBS="-lws2_32 ..." \
+    --prefix="C:/openvswitch/usr" --localstatedir="C:/openvswitch/var" \
+    --sysconfdir="C:/openvswitch/etc"
+
+* Run make for the ported executables in the top source directory, e.g.:
+
+  % make utilities/ovs-vsctl.exe ovsdb/ovsdb-server.exe