Switch platform EH unwinder to prebuilt LLVM libunwind

For the platform libc++ STL, remove the
-Wl,--exclude-libs,libunwind_llvm.a argument, which is redundant with
the same argument in deviceGlobalLdflags.

Bug: http://b/153025717
Test: device boots
Change-Id: Idd7791d52f74aab2d5f59419fb75f841fc29a2eb
diff --git a/apex/allowed_deps.txt b/apex/allowed_deps.txt
index 57b18de..f59408e 100644
--- a/apex/allowed_deps.txt
+++ b/apex/allowed_deps.txt
@@ -564,6 +564,7 @@
 prebuilt_libclang_rt.builtins-arm-android(minSdkVersion:(no version))
 prebuilt_libclang_rt.builtins-i686-android(minSdkVersion:(no version))
 prebuilt_libclang_rt.builtins-x86_64-android(minSdkVersion:(no version))
+prebuilt_libunwind(minSdkVersion:(no version))
 prebuilt_test_framework-sdkextensions(minSdkVersion:(no version))
 server_configurable_flags(minSdkVersion:29)
 service-permission(minSdkVersion:current)
diff --git a/apex/apex.go b/apex/apex.go
index 5cd18ed..bff7793 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -2854,7 +2854,7 @@
 		"libprofile-clang-extras_ndk",
 		"libprofile-extras",
 		"libprofile-extras_ndk",
-		"libunwind_llvm",
+		"libunwind",
 	}
 	return m
 }
diff --git a/apex/apex_test.go b/apex/apex_test.go
index fc74672..ddbbe38 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -1751,10 +1751,10 @@
 
 	// ensure apex variant of c++ is linked with static unwinder
 	cm := ctx.ModuleForTests("libc++", "android_arm64_armv8-a_shared_apex29").Module().(*cc.Module)
-	ensureListContains(t, cm.Properties.AndroidMkStaticLibs, "libgcc_stripped")
+	ensureListContains(t, cm.Properties.AndroidMkStaticLibs, "libunwind")
 	// note that platform variant is not.
 	cm = ctx.ModuleForTests("libc++", "android_arm64_armv8-a_shared").Module().(*cc.Module)
-	ensureListNotContains(t, cm.Properties.AndroidMkStaticLibs, "libgcc_stripped")
+	ensureListNotContains(t, cm.Properties.AndroidMkStaticLibs, "libunwind")
 }
 
 func TestApexMinSdkVersion_ErrorIfIncompatibleStubs(t *testing.T) {