Rename test-abi to test-symbols, start verifying symbols are documented

We keep forgetting to update `apidoc/ostree-sections.txt`, so let's
start enforcing it.  Of course it turns out we had some bugs here
like symbols marked as public but never implemented, etc.  Those
are fixed in the prior commits.

Closes: #263
Approved by: giuseppe

tests/test-symbols.sh

@@ -19,10 +19,19 @@
 
 set -euo pipefail
 
-echo '1..1'
+echo '1..2'
 
+echo "Verifying all expected symbols are actually exported..."
 grep ' ostree_[A-Za-z0-9_]*;' ${G_TEST_SRCDIR}/src/libostree/libostree.sym | sed -e 's,^ *\([A-Za-z0-9_]*\);,\1,' | sort -u > expected-symbols.txt
 eu-readelf -a ${G_TEST_BUILDDIR}/.libs/libostree-1.so | grep 'FUNC.*GLOBAL.*DEFAULT.*@@LIBOSTREE_' | sed -e 's,^.* \(ostree_[A-Za-z0-9_]*\)@@LIBOSTREE_[0-9_.]*,\1,' |sort -u > found-symbols.txt
 diff -u expected-symbols.txt found-symbols.txt
+echo "ok exports"
 
-echo 'ok'
+# cmd__private__ is private.  The fetcher symbol should not have been made public.
+grep -E -v '(ostree_cmd__private__)|(ostree_fetcher_config_flags_get_type)' found-symbols.txt > expected-documented.txt
+
+echo "Verifying all public symbols are documented:"
+grep '^ostree_' ${G_TEST_SRCDIR}/apidoc/ostree-sections.txt |sort -u > found-documented.txt
+diff -u expected-documented.txt found-documented.txt
+
+echo 'ok documented symbols'