emulator: add unwindstack

Fix emulator booting
09-03 04:22:19.175  1392  1392 E libEGL  : load_driver(/vendor/lib/egl/libGLES_emulation.so): unknown
09-03 04:22:19.184  1392  1392 E vndksupport: Could not load /vendor/lib/egl/libEGL_emulation.so from sphal namespace: dlopen failed: library "libunwindstack.so" not found.
09-03 04:22:19.184  1392  1392 E libEGL  : load_driver(/vendor/lib/egl/libEGL_emulation.so): unknown
09-03 04:22:19.184  1392  1392 F libEGL  : couldn't find an OpenGL ES implementation
09-03 04:22:19.184  1392  1392 F libc    : Fatal signal 6 (SIGABRT), code -6 in tid 1392 (surfaceflinger), pid 1392 (surfaceflinger)

Test: build sdk_gphone_x86-userdebug, emualtor
should boot to homescreen

Change-Id: Id967e74a0b0ec76e01a3ef18274da591b48613d1