Use configure.ac provided soname versioning.

Makefile.am

@@ -21,7 +21,7 @@ include silk_headers.mk
 include opus_headers.mk
 
 libopus_la_SOURCES = $(CELT_SOURCES) $(SILK_SOURCES) $(OPUS_SOURCES)
-libopus_la_LDFLAGS = -no-undefined -version-info 2:0:2
+libopus_la_LDFLAGS = -no-undefined -version-info @OPUS_LT_CURRENT@:@OPUS_LT_REVISION@:@OPUS_LT_AGE@
 
 pkginclude_HEADERS = include/opus.h include/opus_multistream.h include/opus_types.h include/opus_defines.h
 

configure.ac

@@ -37,9 +37,9 @@ AC_DEFINE_UNQUOTED(OPUS_MICRO_VERSION, ${OPUS_MICRO_VERSION}, [Version micro])
 AC_DEFINE_UNQUOTED(OPUS_EXTRA_VERSION, "${OPUS_EXTRA_VERSION}", [Version extra])
 
 # For libtool.
-OPUS_LT_CURRENT=0
+OPUS_LT_CURRENT=2
 OPUS_LT_REVISION=0
-OPUS_LT_AGE=0
+OPUS_LT_AGE=2
 
 AC_SUBST(OPUS_LT_CURRENT)
 AC_SUBST(OPUS_LT_REVISION)