gfxstream: guest: introduce Gralloc::getGrallocType()

This API tells the user whether the chosen
implementation is goldfish gralloc, cros_gralloc
(minigbm), or emulated gralloc.

Use with caution.

Reviewed-by: Aaron Ruby <aruby@blackberry.com>
Acked-by: Yonggang Luo <luoyonggang@gmail.com>
Acked-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/27246>

src/gfxstream/guest/android/GrallocEmulated.h

@@ -67,6 +67,8 @@ class EmulatedGralloc : public Gralloc {
    public:
     EmulatedGralloc(VirtGpuDevice* device);
     ~EmulatedGralloc();
+
+    GrallocType getGrallocType() override;
     uint32_t createColorBuffer(void*, int width, int height, uint32_t glFormat) override;
 
     int allocate(uint32_t width, uint32_t height, uint32_t format, uint64_t usage,