fltk: Fix compilation and distcheck errors.
* fltk/Makefile.am (AM_CXXFLAGS): Add -std=c++11 flag. (pinentry_fltk_SOURCES): Add header files. (EXTRA_DIST): Add icon files. * .gitignore: Ignore autoconf-generated files in fltk/.
The FLTK pinentry requires C++11 due to the use of std::unique_ptr.
- Signed-off-by: Damien Goutte-Gattat <dgouttegattat@incenp.org>