Ignore static-ruby [ci skip]

static-ruby is statically linked against libruby, even when
configured with --enable-shared.

.gitignore

@@ -128,6 +128,7 @@ lcov*.info
 /ruby-man.rd.gz
 /run.gdb
 /sizes.c
+/static-ruby
 /test.rb
 /test-coverage.dat
 /tmp