libexif-gtk does libtool library versioning different than libexif - and only one can be right

[ndim]

I have just stumbled across the way libexif-gtk does its soname versioning which appears to differ from the way libexif does it.

Summarizing:

• libexif-gtk uses --version-info $(($CURRENT + $REVISION)):$AGE:$REVISION.
• libexif uses --version-info $CURRENT:$AGE:$REVISION

while the descriptions for the *_CURRENT, *_REVISION, and _AGE numbers are the same.

This is what libexif-gtk does, in more detail:

LIBEXIF_GTK_AGE=0
LIBEXIF_GTK_REVISION=1
LIBEXIF_GTK_CURRENT=5
AC_SUBST([LIBEXIF_GTK_AGE])
AC_SUBST([LIBEXIF_GTK_REVISION])
AC_SUBST([LIBEXIF_GTK_CURRENT])
LIBEXIF_GTK_VERSION_INFO=`expr $LIBEXIF_GTK_CURRENT + $LIBEXIF_GTK_REVISION`:$LIBEXIF_GTK_AGE:$LIBEXIF_GTK_REVISION
AC_SUBST([LIBEXIF_GTK_VERSION_INFO])

libexif-gtk/Makefile.am:libexif_@LIBEXIF_GTK_EXTENSION@_la_LDFLAGS = -version-info @LIBEXIF_GTK_VERSION_INFO@

For comparison, this is what libexif does:

LIBEXIF_CURRENT=15
LIBEXIF_AGE=3
LIBEXIF_REVISION=4
AC_SUBST([LIBEXIF_AGE])
AC_SUBST([LIBEXIF_REVISION])
AC_SUBST([LIBEXIF_CURRENT])
AC_SUBST([LIBEXIF_CURRENT_MIN],[`expr $LIBEXIF_CURRENT - $LIBEXIF_AGE`])
LIBEXIF_VERSION_INFO="$LIBEXIF_CURRENT:$LIBEXIF_REVISION:$LIBEXIF_AGE"
AC_SUBST([LIBEXIF_VERSION_INFO])

libexif/Makefile.am:    -no-undefined -version-info @LIBEXIF_VERSION_INFO@

libgphoto2 does the same thing libexif does, so I presume libexif-gtk is the odd one out here and should be fixed to use the same mechanism, correct?