[CMake] Fix typo "Wraning" (NFC)

Summary:
The typo was added in https://reviews.llvm.org/rL247151.
It should be "warning", not "wraning".



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314486 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -795,7 +795,7 @@ if(LLVM_USE_HOST_TOOLS)
   include(CrossCompile)
 endif(LLVM_USE_HOST_TOOLS)
 if(LLVM_TARGET_IS_CROSSCOMPILE_HOST)
-# Dummy use to avoid CMake Wraning: Manually-specified variables were not used
+# Dummy use to avoid CMake Warning: Manually-specified variables were not used
 # (this is a variable that CrossCompile sets on recursive invocations)
 endif()