Use standard shared library versioning.

Index: gettext-tools/src/Makefile.in
--- gettext-tools/src/Makefile.in.orig
+++ gettext-tools/src/Makefile.in
@@ -4417,7 +4417,7 @@ libgettextsrc_la_DEPENDENCIES = $(WOE32_LIBADD)
 # Need @LTLIBINTL@ because many source files use gettext().
 # Need @LTLIBICONV@ because po-charset.c, read-po-lex.c, msgl-iconv.c,
 # write-po.c use iconv().
-libgettextsrc_la_LDFLAGS = -release @VERSION@ \
+libgettextsrc_la_LDFLAGS = \
 	../gnulib-lib/libgettextlib.la $(LTLIBUNISTRING) \
 	$(LT_LIBTEXTSTYLE) @LTLIBINTL@ @LTLIBICONV@ -lc -no-undefined \
 	$(am__append_6) $(am__append_8) $(am__append_10)
