Add execinfo functionality.

Bug: 27877410

Test: Add new unit tests.
Change-Id: Id5d7eb27a23f50e99a04f5ee1ab64047ba269bab
diff --git a/libc/Android.bp b/libc/Android.bp
index 2a8df9a..ee8c280 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1054,6 +1054,7 @@
         "bionic/error.cpp",
         "bionic/eventfd.cpp",
         "bionic/exec.cpp",
+        "bionic/execinfo.cpp",
         "bionic/faccessat.cpp",
         "bionic/fchmod.cpp",
         "bionic/fchmodat.cpp",