[devhelp] build: AC_SUBST only one variable for the libtool version

[Sébastien Wilmet <swilmet src gnome org>]

commit 1fcc94458c237c8ab3e3f8e79db6789eb510b772
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed May 10 14:39:46 2017 +0200

    build: AC_SUBST only one variable for the libtool version

 configure.ac    |   12 +++++-------
 src/Makefile.am |   10 +++++-----
 2 files changed, 10 insertions(+), 12 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index d948cdb..ad42694 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,13 +12,11 @@ AX_IS_RELEASE([git-directory])
 #   (Interfaces removed:    CURRENT++, AGE=0, REVISION=0)
 #   (Interfaces added:      CURRENT++, AGE++, REVISION=0)
 #   (No interfaces changed:                   REVISION++)
-LIBDEVHELP_CURRENT=3
-LIBDEVHELP_AGE=0
-LIBDEVHELP_REVISION=0
-
-AC_SUBST(LIBDEVHELP_CURRENT)
-AC_SUBST(LIBDEVHELP_AGE)
-AC_SUBST(LIBDEVHELP_REVISION)
+LIBDEVHELP_LT_CURRENT=3
+LIBDEVHELP_LT_REVISION=0
+LIBDEVHELP_LT_AGE=0
+LIBDEVHELP_LT_VERSION="$LIBDEVHELP_LT_CURRENT:$LIBDEVHELP_LT_REVISION:$LIBDEVHELP_LT_AGE"
+AC_SUBST([LIBDEVHELP_LT_VERSION])
 
 AC_CONFIG_HEADERS(config.h)
 AC_CONFIG_SRCDIR(src/dh-main.c)
diff --git a/src/Makefile.am b/src/Makefile.am
index f438292..093a455 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -125,11 +125,11 @@ libdevhelp_3_la_LIBADD =  \
        $(ZLIB_LIBS)            \
        $(LIBM)
 
-libdevhelp_3_la_LDFLAGS =                                                              \
-       $(AM_LDFLAGS)                                                                   \
-       -no-undefined                                                                   \
-       -version-info ${LIBDEVHELP_CURRENT}:${LIBDEVHELP_REVISION}:${LIBDEVHELP_AGE}    \
-       -export-symbols-regex ^dh_                                                      \
+libdevhelp_3_la_LDFLAGS =                      \
+       $(AM_LDFLAGS)                           \
+       -no-undefined                           \
+       -version-info $(LIBDEVHELP_LT_VERSION)  \
+       -export-symbols-regex ^dh_              \
        $(ZLIB_LDFLAGS)
 
 # The application