Initialize a variable to quite a compiler warning.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@163576 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Target/Thread.cpp b/source/Target/Thread.cpp
index 4b4f85a..05ab150 100644
--- a/source/Target/Thread.cpp
+++ b/source/Target/Thread.cpp
@@ -955,7 +955,7 @@
     {
 
         int master_plan_idx;
-        bool discard;
+        bool discard = true;
 
         // Find the first master plan, see if it wants discarding, and if yes discard up to it.
         for (master_plan_idx = m_plan_stack.size() - 1; master_plan_idx >= 0; master_plan_idx--)