Make libdvr a shared library

Make libdvr a shared library so it can be loaded by the vr platform
library and accessed externally.

Bug: 38134403
Test: Booted a Marlin.

Change-Id: I9914188c80a9a41902fc4000a4f78f877e5e5695
diff --git a/libs/vr/libdvr/dvr_api.cpp b/libs/vr/libdvr/dvr_api.cpp
index 4d7e1a6..2c95583 100644
--- a/libs/vr/libdvr/dvr_api.cpp
+++ b/libs/vr/libdvr/dvr_api.cpp
@@ -18,7 +18,7 @@
 
 extern "C" {
 
-DVR_EXPORT int dvrGetApi(void* api, size_t struct_size, int version) {
+int dvrGetApi(void* api, size_t struct_size, int version) {
   ALOGI("dvrGetApi: api=%p struct_size=%zu version=%d", api, struct_size,
         version);
   if (version == 1) {