.gitignore: add autotools' `compile`
.gitignore: add autotools' `compile`

Since automake 1.14, autotools now generate a symbolic link named
`compile` in the root of the repository when running, so let's include
it in .gitignore to achieve a clean `git status` after compiling (or
avoid breaking the build via `git clean -fd`).

Signed-off-by: Bertrand Lorentz <eb7ac131ef7bff6d2ebccd6e5bf9a7cb6485cf2c@gmail.com>

orion75/gtk-sharp,antoniusriha/gtk-sharp,orion75/gtk-sharp,orion75/gtk-sharp,orion75/gtk-sharp,antoniusriha/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp,antoniusriha/gtk-sharp,sillsdev/gtk-sharp,sillsdev/gtk-sharp,sillsdev/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp,antoniusriha/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp,sillsdev/gtk-sharp,antoniusriha/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,orion75/gtk-sharp,sillsdev/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp