* cfg.mk: Multiple changes.
(sc_GPL_version): Don't exclude all files when only one has a parsing
issue
(sc_po_check): Tests should always output English. Their output is for
developers, not users
(sc_prohibit_magic_number_exit): tests/test-plugin.c has a parsing
issue that has been reported to gnulib. Others should be checked.
(sc_trailing_blank): Fixed the relevant files instead of ignoring them
(sc_two_space_separator_in_usage): Doesn't seem to trigger on removal
(sc_prohibit_empty_lines_at_EOF): Same
(sc_prohibit_sprintf): Same
(sc_prohibit_printf): Re-arrange within file
(sc_prohibit_free): Same
(sc_prohibit_alloc): Same
(sc_gettext_printf): Same
* docs/DoxygenLayout.xml: Remove trailing whitespaces
* docs/libwget.doxy.in: Same
* tests/libtest.c: Don't internationalize test suite strings
* tests/test-*.c: Use EXIT_FAILURE and EXIT_SUCCESS instead of 1 and 0
* tests/libtest.{c,h}: Add support for feature flags during test
startup. Check if Wget2 is compiled with the feature and conditionally
SKIP the tests
* tests/test-*.c: Pass the right feature flags for each test. MHD for
HTTP, FTP for FTP, IDN and PLUGIN when applicable
