tools/pygrub: add .gitignore file

Add a local .gitignore file for tools/pygrub.

As at least on some systems (e.g. OpenSUSE Leap 15.5) the build will
produce a tools/pygrub/pygrub.egg-info directory, add it to the new
.gitignore file, too.

Use "/dir/" as pattern for ignoring a directory and its contents, as
the "/dir/*" pattern won't ignore the directory itself (git just
doesn't complain when seeing a directory without any not ignored file
in it).

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

.gitignore

@@ -213,7 +213,6 @@ tools/misc/xencov
 tools/pkg-config/*
 tools/qemu-xen-build
 tools/xentrace/xenalyze
-tools/pygrub/build/*
 tools/python/build/*
 tools/tests/depriv/depriv-fd-checker
 tools/tests/x86_emulator/*.bin