maint: implement proper library versioning. * libcruft/Makefile.am (libcruft_current): New variable. (libcruft_revision): Likewise. (libcruft_age): Likewise. (libcruft_version_info): Likewise. (libcruft_la_LDFLAGS): Use -version-info option, not -release. * liboctave/Makefile.am (liboctave_current): New variable. (liboctave_revision): Likewise. (liboctave_age): Likewise. (liboctave_version_info): Likewise. (liboctave_la_LDFLAGS): Use -version-info option, not -release. * liboctinterp/Makefile.am (liboctinterp_current): New variable. (liboctinterp_revision): Likewise. (liboctinterp_age): Likewise. (liboctinterp_version_info): Likewise. (liboctinterp_la_LDFLAGS): Use -version-info option, not -release.

--- a/liboctave/Makefile.am
+++ b/liboctave/Makefile.am
@@ -526,7 +526,17 @@
   $(ARPACK_CPPFLAGS) \
   $(AM_CPPFLAGS)
 
-liboctave_la_LDFLAGS = -release $(version) $(NO_UNDEFINED_LDFLAG) \
+# Increment these as needed and according to the rules in the libtool
+# manual:
+liboctave_current = 0
+liboctave_revision = 0
+liboctave_age = 0
+
+liboctave_version_info = $(liboctave_current):$(liboctave_revision):$(liboctave_age)
+
+liboctave_la_LDFLAGS = \
+  -version-info $(liboctave_version_info) \
+  $(NO_UNDEFINED_LDFLAG) \
   -bindir $(bindir) \
   $(SPARSE_XLDFLAGS) \
   $(ARPACK_LDFLAGS) \