Include a useful version number on installed shared libraries

Prompted by Ole Streicher for use with the Debian AST package. It uses
the numering scheme described at

https://phab.enlightenment.org/w/autotoolsintegration/

under "Versioning of the shared library"? That is:

soname_current = package_minor + package_major
soname_revision = package_micro
soname_age = package_minor

Makefile.am

@@ -672,6 +672,7 @@ libast_la_SOURCES = \
     $(CMINPACK_FILES) \
     $(WCSLIB_FILES) \
     ast_err.h
+libast_la_LDFLAGS = -version-info @version_info@
 
 # Ensure libast links against libraries containing functions used within
 # libast. If AST is configured --with-external-pal, then the internal
@@ -691,37 +692,47 @@ nodist_libast_la_SOURCES = \
 
 #  The default error reporting module.
 libast_err_la_SOURCES = err_null.c
+libast_err_la_LDFLAGS = -version-info @version_info@
 
 #  The error reporting module that uses EMS to deliver errors.
 libast_ems_la_SOURCES = err_ems.c
+libast_ems_la_LDFLAGS = -version-info @version_info@
 
 #  The error reporting module that uses DRAMA Ers to deliver errors.
 libast_drama_la_SOURCES = err_drama.c
+libast_drama_la_LDFLAGS = -version-info @version_info@
 
 #  The module containing null implementations of the 3D graphics routines
 #  required by AST
 libast_grf3d_la_SOURCES = grf3d.c
+libast_grf3d_la_LDFLAGS = -version-info @version_info@
 
 #  The module containing null implementations of the graphics routines
 #  required by AST V2.0
 libast_grf_2_0_la_SOURCES = grf_2.0.c
+libast_grf_2_0_la_LDFLAGS = -version-info @version_info@
 
 #  The module containing null implementations of the graphics routines
 #  added by AST V3.2 and not present in V2.0
 libast_grf_3_2_la_SOURCES = grf_3.2.c
+libast_grf_3_2_la_LDFLAGS = -version-info @version_info@
 
 #  The module containing null implementations of the graphics routines
 #  added by AST V5.6 and not present in V3.2
 libast_grf_5_6_la_SOURCES = grf_5.6.c
+libast_grf_5_6_la_LDFLAGS = -version-info @version_info@
 
 #  The graphics module that uses PGPLOT for 2D graphical output.
 libast_pgplot_la_SOURCES = $(GRF_PGPLOT_SOURCES)
+libast_pgplot_la_LDFLAGS = -version-info @version_info@
 
 #  The graphics module that uses PGPLOT for 3D graphical output.
 libast_pgplot3d_la_SOURCES = $(GRF3D_PGPLOT_SOURCES)
+libast_pgplot3d_la_LDFLAGS = -version-info @version_info@
 
 #  Positional astronomy libraries.
 libast_pal_la_SOURCES = $(PAL_FILES)
+libast_pal_la_LDFLAGS = -version-info @version_info@
 
 # The following files are built by the targets in this makefile.
 MAINTAINERCLEANFILES = version.h builddocs addversion \

component.xml

@@ -2,7 +2,7 @@
 <!DOCTYPE component SYSTEM "componentinfo.dtd">
 
 <component id="ast" support="S">
-  <version>9.0.0</version>
+  <version>9.0.1</version>
   <path>libext/ast</path>
   <description>WCS library</description>
   <abstract>

configure.ac

@@ -7,9 +7,20 @@ dnl   1.5.  It should work with autoconf versions 2.50 or better, and
 dnl   automake 1.6 or better.
 
 dnl   Initialisation: package name and version number
-AC_INIT([ast],[9.0.0],[[email protected]])
+m4_define([v_maj], [9])
+m4_define([v_min], [0])
+m4_define([v_mic], [1])
+m4_define([project_version], [v_maj.v_min.v_mic])
+AC_INIT([ast],[project_version],[[email protected]])
 AC_CONFIG_AUX_DIR([build-aux])
 
+dnl   Shared library versioning
+m4_define([lt_cur], [m4_eval(v_maj + v_min)])
+m4_define([lt_rev], [v_mic])
+m4_define([lt_age], [v_min])
+version_info="lt_cur:lt_rev:lt_age"
+AC_SUBST([version_info])
+
 dnl   Require autoconf-2.50 at least
 AC_PREREQ([2.69])
 dnl   Require Starlink automake