Fold init() helpers into constructors. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231486 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ExecutionEngine/ExecutionEngine.h

@@ -510,9 +510,6 @@ private:
   bool VerifyModules;
   bool UseOrcMCJITReplacement;
 
-  /// InitEngine - Does the common initialization of default options.
-  void InitEngine();
-
 public:
   /// Default constructor for EngineBuilder.
   EngineBuilder();