Introduce Gfxstream Features to decouple Gfxstream from AEMU

... which will allow building Gfxstream from a fixed version of
AEMU for the purposes of packaging.

Bug: b/326648397
Test: cvd start --gpu_mode=gfxstream
Test: cvd start --gpu_mode=gfxstream_guest_angle
Change-Id: I8ac1622428f0194997597868bef49118bcc3ea90
diff --git a/host/Android.bp b/host/Android.bp
index 426193f..fc82941 100644
--- a/host/Android.bp
+++ b/host/Android.bp
@@ -35,6 +35,7 @@
         "gfxstream_base",
         "gfxstream_host_common",
         "libgfxstream_common_utils",
+        "libgfxstream_host_features",
         "libgfxstream_etc",
         "libgfxstream_glestranslator_egl",
         "libgfxstream_glestranslator_glescm",
@@ -58,6 +59,7 @@
     ],
     export_static_lib_headers: [
         "gfxstream_base",
+        "libgfxstream_host_features",
         "libgfxstream_host_gl_host_common",
         "libgfxstream_host_gles2_dec",
         "libgfxstream_host_glsnapshot",