add testcase

tests/assert/tfailedassert_stacktrace.nim

@@ -0,0 +1,19 @@
+discard """
+  output: '''
+tfailedassert_stacktrace.nim(16) tfailedassert_stacktrace
+tfailedassert_stacktrace.nim(15) foo
+system.nim(3777)         failedAssertImpl
+system.nim(3770)         raiseAssert
+system.nim(2817)         sysFatal
+'''
+"""
+
+
+
+try:
+  proc foo() =
+    assert(false)
+  foo()
+except AssertionError:
+  let e = getCurrentException()
+  echo e.getStackTrace