[PATCH v4] Improve Windows build documentation

[Martin Bonner]

* Add three more modules that are required.
* Remove the version numbers (because they are hard to keep in sync
  with the latest MSYS2 versions)
* Add a pacman command line to install everything.

Signed-off-by: Martin Bonner <martingreybeard at gmail.com>
---
 doc/build/tools.rst | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/doc/build/tools.rst b/doc/build/tools.rst
index c06f915274..5f8a04a31b 100644
--- a/doc/build/tools.rst
+++ b/doc/build/tools.rst
@@ -24,14 +24,20 @@ you can use MSYS2, a software distro and building
platform for Windows.
 Download the MSYS2 installer from https://www.msys2.org. Make sure you have
 installed all required packages below in order to build these host tools::

-   * gcc (9.1.0)
-   * make (4.2.1)
-   * bison (3.4.2)
-   * diffutils (3.7)
-   * openssl-devel (1.1.1.d)
-
-Note the version numbers in these parentheses above are the package
versions
-at the time being when writing this document. The MSYS2 installer tested is
+   * gcc
+   * make
+   * bison
+   * diffutils
+   * openssl-devel
+   * flex
+   * libgnutls-devel
+   * libuuid-devel
+
+You probably want ``git`` as well.  You can install all these with::
+
+    $ pacman -S gcc make bison diffutils openssl-devel flex
libgnutls-devel libuuid-devel git
+
+The MSYS2 installer tested is
 http://repo.msys2.org/distrib/x86_64/msys2-x86_64-20190524.exe.

 There are 3 MSYS subsystems installed: MSYS2, MinGW32 and MinGW64. Each
-- 
Martin Bonner