[SystemZ] Add MCJIT support

Another step towards reinstating the SystemZ backend.  I'll commit
the configure changes separately (TARGET_HAS_JIT etc.), then commit
a patch to enable the MCJIT tests on SystemZ.

llvm-svn: 181015
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
index 51873b1..9d767a0 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
@@ -172,10 +172,19 @@
       return 16;
     else if (Arch == Triple::ppc64)
       return 44;
+    else if (Arch == Triple::systemz)
+      return 16;
     else
       return 0;
   }
 
+  inline unsigned getStubAlignment() {
+    if (Arch == Triple::systemz)
+      return 8;
+    else
+      return 1;
+  }
+
   bool HasError;
   std::string ErrorStr;