Add libunwind_llvm to allowed deps

Needed in an internal branch for certain kinds of builds.

Test: m apex-allowed-deps-check
Change-Id: Ia9a6f19c5591feffdc228aea360c504e46d19055
(cherry picked from commit 2b3b590d185768ce1f24bb53f554819fff2d47da)
diff --git a/build/allowed_deps.txt b/build/allowed_deps.txt
index c984eaf..c5bdbcf 100644
--- a/build/allowed_deps.txt
+++ b/build/allowed_deps.txt
@@ -447,6 +447,7 @@
 libui(minSdkVersion:29)
 libui-types(minSdkVersion:apex_inherit)
 libui_headers(minSdkVersion:29)
+libunwind_llvm(minSdkVersion:apex_inherit)
 libunwindstack(minSdkVersion:29)
 libutf(minSdkVersion:(no version))
 libutils(minSdkVersion:apex_inherit)