Library ABI tracking with abigail

Provide two make targets: checkabi and storeabi.

storeabi uses libabigail to generate a reference copy of the ABI for the
public libraries.

checkabi compares such a reference to the compiled version, failing if
they are not compatible.  No ABI is generated for libzpool.so, it is
only used by ztest and zdb and not external consumers.

Co-authored-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Antonio Russo <aerusso@aerusso.net>
Closes #11144

lib/Makefile.am

@@ -15,4 +15,21 @@ SUBDIRS += libzutil libunicode
 
 # These five libraries, which are installed as the final build product,
 # incorporate the eight convenience libraries given above.
-SUBDIRS += libuutil libzfs_core libzfs libzpool libzfsbootenv
+DISTLIBS = libuutil libzfs_core libzfs libzpool libzfsbootenv
+SUBDIRS += $(DISTLIBS)
+DISTLIBS += libnvpair
+
+# An ABI is stored for each of these libraries.  Note that libzpool.so
+# is only linked against by ztest and zdb and no stable ABI is provided.
+ABILIBS = libnvpair libuutil libzfs_core libzfs libzfsbootenv
+
+PHONY = checkabi storeabi
+checkabi: $(ABILIBS)
+	set -e ; for dir in $(ABILIBS) ; do \
+		$(MAKE) -C $$dir checkabi ; \
+	done
+
+storeabi: $(ABILIBS)
+	set -e ; for dir in $(ABILIBS) ; do \
+		$(MAKE) -C $$dir storeabi ; \
+	done