Move from libbacktrace to libunwindstack.

Use the new AndroidUnwinder object to replace the libbacktrace version.

Bug: 120606663

Test: Run unit tests.
Test: Force a call to CallStack::log() and verify the backtrace is
Test: reasonable.
Change-Id: I73d909821a33f716d7b0e0997d43c6ab11c7c4f9
diff --git a/opengl/libs/Android.bp b/opengl/libs/Android.bp
index c9fce8a..c1e935a 100644
--- a/opengl/libs/Android.bp
+++ b/opengl/libs/Android.bp
@@ -108,7 +108,6 @@
         // In particular, DO NOT add libutils nor anything "above" libui
         "libgraphicsenv",
         "libnativewindow",
-        "libbacktrace",
         "libbase",
     ],
 }
@@ -165,6 +164,7 @@
         "libnativeloader_lazy",
         "libutils",
         "libSurfaceFlingerProp",
+        "libunwindstack",
     ],
     static_libs: [
         "libEGL_getProcAddress",