replace all instances of 'mcjit' flag in tutorial docs with 'orcjit' flag

[bmansfieldRIT]

Summary

Kaleidoscope now uses the ORC JIT engine, orcjit is the correct flag here.

llvm/docs/tutorial/LangImpl04.rst

 =================
 
 Here is the complete code listing for our running example, enhanced with
 the LLVM JIT and optimizer. To build this example, use:
 
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core mcjit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
     # Run
     ./toy
 
 If you are compiling this on Linux, make sure to add the "-rdynamic"
 option as well. This makes sure that the external functions are resolved
 properly at runtime.
 
 Here is the code:
 
 .. literalinclude:: ../../examples/Kaleidoscope/Chapter4/toy.cpp
    :language: c++
 
 `Next: Extending the language: control flow <LangImpl05.html>`_
 

llvm/docs/tutorial/LangImpl05.rst

 =================
 
 Here is the complete code listing for our running example, enhanced with
 the if/then/else and for expressions. To build this example, use:
 
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core mcjit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
     # Run
     ./toy
 
 Here is the code:
 
 .. literalinclude:: ../../examples/Kaleidoscope/Chapter5/toy.cpp
    :language: c++
 
 `Next: Extending the language: user-defined operators <LangImpl06.html>`_
 

llvm/docs/tutorial/LangImpl06.rst

 =================
 
 Here is the complete code listing for our running example, enhanced with
 the support for user-defined operators. To build this example, use:
 
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core mcjit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
     # Run
     ./toy
 
 On some platforms, you will need to specify -rdynamic or
 -Wl,--export-dynamic when linking. This ensures that symbols defined in
 the main executable are exported to the dynamic linker and so are
 available for symbol resolution at run time. This is not needed if you
 compile your support code into a shared library, although doing that

llvm/docs/tutorial/LangImpl07.rst

 =================
 
 Here is the complete code listing for our running example, enhanced with
 mutable variables and var/in support. To build this example, use:
 
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core mcjit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
     # Run
     ./toy
 
 Here is the code:
 
 .. literalinclude:: ../../examples/Kaleidoscope/Chapter7/toy.cpp
    :language: c++
 
 `Next: Compiling to Object Code <LangImpl08.html>`_
 

llvm/docs/tutorial/LangImpl09.rst

 =================
 
 Here is the complete code listing for our running example, enhanced with
 debug information. To build this example, use:
 
 .. code-block:: bash
 
     # Compile
-    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core mcjit native` -O3 -o toy
+    clang++ -g toy.cpp `llvm-config --cxxflags --ldflags --system-libs --libs core orcjit native` -O3 -o toy
     # Run
     ./toy
 
 Here is the code:
 
 .. literalinclude:: ../../examples/Kaleidoscope/Chapter9/toy.cpp
    :language: c++
 
 `Next: Conclusion and other useful LLVM tidbits <LangImpl10.html>`_