gitignore: unignore installed

Users can install the library somewhere else in the path;
no need to give them this option.

Signed-off-by: Emilio G. Cota <cota@braap.org>
automate: add bootstrap script + ignore generated files

Signed-off-by: Emilio G. Cota <cota@braap.org>
automake: do not create missing files

For example, INSTALL, which already exists.

Signed-off-by: Emilio G. Cota <cota@braap.org>
automake: do not track generated files

Signed-off-by: Emilio G. Cota <cota@braap.org>