Summary:
Currently, building through runtimes will yield this warning:
```
CMake Warning at compiler-rt/cmake/Modules/CompilerRTUtils.cmake:335 (message):
LLVMTestingSupport not found in LLVM_AVAILABLE_LIBS
Call Stack (most recent call first)
```
This is due to the fact that the builtins target does not go through the
s tandard runtimes patch and sets them as BUILDTREE_ONLY so they do not
show up. These are not used in this case, so just guard the condition to
suppress the warning.
Compiler-RT ================================ This directory and its subdirectories contain source code for the compiler support routines. Compiler-RT is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. ================================