[PATCH] compat/vcbuild/README: clean/update 'vcpkg' env for Visual Studio updates

[Philip Oakley <philipoakley@iee.org>]

When the user installs an updated version of Visual Studio, the previously
generated MSVC-DEFS-GEN will need to be deleted to allow updating.

Alternatively the whole vcpkg download may be cleaned allowing it to be
reloaded, though this may take much longer on slower connections.

Signed-off-by: Philip Oakley <philipoakley@iee.org>
---

In response to discussions at:
https://github.com/git-for-windows/git/issues/2186

cc: Jeff Hostetler <git@jeffhostetler.com>
cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>

 compat/vcbuild/README | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/compat/vcbuild/README b/compat/vcbuild/README
index 81da36a93b..40695fc1cc 100644
--- a/compat/vcbuild/README
+++ b/compat/vcbuild/README
@@ -18,6 +18,13 @@ The Steps to Build Git with VS2015 or VS2017 from the command line.
    Makefile:
       <repo_root>/compat/vcbuild/MSVC-DEFS-GEN
 
+   - If you update your Visual Studio version, then delete the MSVC-DEFS-GEN
+   file so that fresh environment variables can be discovered.
+
+   Or clean the "vcpkg" environment with:
+
+   $ make MSVC=1 clean
+
 2. OPTIONALLY copy the third-party *.dll and *.pdb files into the repo
    root to make it easier to run and debug git.exe without having to
    manipulate your PATH.  This is especially true for debug sessions in
-- 
2.22.0.rc1.windows.1