[lldb] D66174 `RegularExpression` cleanup

I find as a good cleanup to drop the Compile method. As I do not find TIMTOWTDI
as an advantage and there is already constructor parameter to compile the
regex.

Differential Revision: https://reviews.llvm.org/D66392

llvm-svn: 369352
diff --git a/lldb/source/Target/ThreadPlanStepInRange.cpp b/lldb/source/Target/ThreadPlanStepInRange.cpp
index a0549c8..71045cc 100644
--- a/lldb/source/Target/ThreadPlanStepInRange.cpp
+++ b/lldb/source/Target/ThreadPlanStepInRange.cpp
@@ -313,10 +313,10 @@
 
 void ThreadPlanStepInRange::SetAvoidRegexp(const char *name) {
   auto name_ref = llvm::StringRef::withNullAsEmpty(name);
-  if (!m_avoid_regexp_up)
+  if (m_avoid_regexp_up)
+    *m_avoid_regexp_up = RegularExpression(name_ref);
+  else
     m_avoid_regexp_up.reset(new RegularExpression(name_ref));
-
-  m_avoid_regexp_up->Compile(name_ref);
 }
 
 void ThreadPlanStepInRange::SetDefaultFlagValue(uint32_t new_value) {