Revert "Enable strict unwind check in gcstress."

This reverts commit fae2be2c98acbd4d9b1c493972c2c9770e3b77fc.

Reason for revert: Found failing unwinds

Change-Id: Id4fb53ff1e3fc28bcf74b811a9e6a67d96843160
diff --git a/runtime/backtrace_helper.cc b/runtime/backtrace_helper.cc
index f16a45f..843b403 100644
--- a/runtime/backtrace_helper.cc
+++ b/runtime/backtrace_helper.cc
@@ -46,7 +46,7 @@
 
 // Strict integrity check of the backtrace:
 // All methods must have a name, all the way to "main".
-static constexpr bool kStrictUnwindChecks = true;
+static constexpr bool kStrictUnwindChecks = false;
 
 struct UnwindHelper : public TLSData {
   static constexpr const char* kTlsKey = "UnwindHelper::kTlsKey";