Get some more debugging for ckati crashes

The crash we're following is likely a stack overflow. Use an alternate
stack to actually get the backtraces.

Also write out ulimit to reference what the stack size should be.

Bug: 36182021
Test: ulimit -s 768; build/soong/build_test.bash
Change-Id: I8826e5e53f38af552c8b80a1a8a490fde55f2d4b

build_test.bash

@@ -34,6 +34,8 @@ source "${TOP}/build/soong/scripts/microfactory.bash"
 case $(uname) in
   Linux)
     export LD_PRELOAD=/lib/x86_64-linux-gnu/libSegFault.so
+    export SEGFAULT_USE_ALTSTACK=1
+    ulimit -a
     ;;
 esac