Ignore cscope's cscope.out file

[petdance]

From #233 from @rkta

Maybe you could add cscope's cscope.out (not sure if you could detect the file type independent from the name)?

Using ack with vim's quickfix list it is really annoying if you step accidentally into a several hundred MB cscope database.

[petdance]

Is it a big flat text file like ctags's Tags file?

[rkta]

From what I can tell it is a text file, though I sometimes see characters my terminal can't display.

The only documentation I could find is ftp://ftp.eeng.dcu.ie/pub/ee454/cygwin/usr/share/doc/mlcscope-14.1.8/html/cscope.html under section SYMBOL DATABASE FORMAT.

Files seem to start with cscope <format version> <current dir> [-c] [-q <symbols>] [-T] <trailer offset> with <format version> being an integer.

Example from my system would be:

cscope 15 $HOME/code/newlib-2.4.0.20160527               0020122850