Add getter functions for the interface data symbols

Having these symbols be available as functions rather than data is
occasionally more convenient. Implemented this way rather than a
get-codec-by-id style to avoid creating a link-time dependency
between the encoder and the decoder.

Fixes issue #169

Change-Id: I319f281277033a5e7e3ee3b092b9a87cce2f463d

vp8/exports_dec

diff --git a/vp8/exports_dec b/vp8/exports_dec
index f9b985c..100ac5c 100644
--- a/vp8/exports_dec
+++ b/vp8/exports_dec
@@ -1 +1,2 @@
 data vpx_codec_vp8_dx_algo
+text vpx_codec_vp8_dx

vp8/exports_enc

diff --git a/vp8/exports_enc b/vp8/exports_enc
index 9967011..29ff35e 100644
--- a/vp8/exports_enc
+++ b/vp8/exports_enc
@@ -1 +1,2 @@
 data vpx_codec_vp8_cx_algo
+text vpx_codec_vp8_cx

vp8/vp8_cx_iface.c

diff --git a/vp8/vp8_cx_iface.c b/vp8/vp8_cx_iface.c
index e3f99c0..f8a4de8 100644
--- a/vp8/vp8_cx_iface.c
+++ b/vp8/vp8_cx_iface.c
@@ -1079,7 +1079,7 @@
 #ifndef VERSION_STRING
 #define VERSION_STRING
 #endif
-vpx_codec_iface_t vpx_codec_vp8_cx_algo =
+CODEC_INTERFACE(vpx_codec_vp8_cx) =
 {
     "WebM Project VP8 Encoder" VERSION_STRING,
     VPX_CODEC_INTERNAL_ABI_VERSION,

vp8/vp8_dx_iface.c

diff --git a/vp8/vp8_dx_iface.c b/vp8/vp8_dx_iface.c
index e7e5356..f19cb9a 100644
--- a/vp8/vp8_dx_iface.c
+++ b/vp8/vp8_dx_iface.c
@@ -653,7 +653,7 @@
 #ifndef VERSION_STRING
 #define VERSION_STRING
 #endif
-vpx_codec_iface_t vpx_codec_vp8_dx_algo =
+CODEC_INTERFACE(vpx_codec_vp8_dx) =
 {
     "WebM Project VP8 Decoder" VERSION_STRING,
     VPX_CODEC_INTERNAL_ABI_VERSION,