adbd: compile for host.

Preparatory step for testing adb on GCE on non-linux hosts: instead of
pointing them at a device (emulated or otherwise), point them at adbd
running on a linux host instead.

Test: adbd & adb connect localhost:5555; adb -e wait-for-device shell
Change-Id: Ib22d51a4fc9e6e68f71bf1b3b9b2e1b0bd844760
diff --git a/daemon/framebuffer_service.h b/daemon/framebuffer_service.h
index 264da59..bab44be 100644
--- a/daemon/framebuffer_service.h
+++ b/daemon/framebuffer_service.h
@@ -18,4 +18,6 @@
 
 #include "adb_unique_fd.h"
 
+#if defined(__ANDROID__)
 void framebuffer_service(unique_fd fd);
+#endif