It is unclear from looking at 22f186c9f5 (Add vim package., 2013-11-05)
why its `package` function needed to invoke `make install` twice.
Whatever reason there might have been, it does not look as if it should
be necessary anymore. So let's drop the first one, assuming that the
second invocation would have fixed whatever the first invocation got
wrong.
Incidentally, this patch fixes the build of newer `vim` versions that
would otherwise fail like this:
[...]
cd /C/_/vim/pkg/vim/usr/bin; ln -s vim.exe ex
ln: failed to create symbolic link 'ex': File exists
make[1]: *** [Makefile:2693: /C/_/vim/pkg/vim/usr/bin/ex] Error 1
make[1]: Leaving directory '/C/_/vim/src/vim-9.0.1907/src'
make: *** [Makefile:39: install] Error 2
==> ERROR: A failure occurred in package().
Aborting...
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>