meson: fix debug build on Android

debug_stack functions are implemented in another file for Android.
Also add backtrace library dependency.

Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Reviewed-bu: Kristian H. Kristensen <hoegsber@google.com>
Signed-off-by: Dominik Behr <dbehr@chromium.org>
Acked-by: Dylan Baker <dylan@pnwbakers.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2435>
diff --git a/meson.build b/meson.build
index 86824bd..cb275e7 100644
--- a/meson.build
+++ b/meson.build
@@ -786,6 +786,9 @@
     dependency('hardware'),
     dependency('sync'),
   ]
+  if with_gallium
+    dep_android += dependency('backtrace')
+  endif
   if get_option('platform-sdk-version') >= 26
     dep_android += dependency('nativewindow')
   endif
diff --git a/src/gallium/auxiliary/meson.build b/src/gallium/auxiliary/meson.build
index e79d2ac..7db7614 100644
--- a/src/gallium/auxiliary/meson.build
+++ b/src/gallium/auxiliary/meson.build
@@ -246,7 +246,6 @@
   'util/u_debug_image.h',
   'util/u_debug_refcnt.c',
   'util/u_debug_refcnt.h',
-  'util/u_debug_stack.c',
   'util/u_debug_stack.h',
   'util/u_debug_symbol.c',
   'util/u_debug_symbol.h',
@@ -339,6 +338,16 @@
   'nir/nir_draw_helpers.h',
 )
 
+if with_platform_android
+  files_libgallium += files(
+    'util/u_debug_stack_android.cpp',
+  )
+else
+  files_libgallium += files(
+    'util/u_debug_stack.c',
+  )
+endif
+
 if dep_libdrm.found()
   files_libgallium += files(
     'renderonly/renderonly.c',