... to allow rolling SwiftShader for Android.

external/swiftshader/third_party/llvm-10.0/llvm/lib/Support/
ManagedStatic.cpp:21:30: error: unused variable 'ManagedStaticMutex'

external/swiftshader/third_party/llvm-10.0/llvm/lib/Support/
ManagedStatic.cpp:22:24: error: unused variable 'mutex_init_flag'

Bug: b/171498948
Test: build inside Android repo
Change-Id: Idc3ab2ef4de759c14499454f5d841b750124686b
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52648
Presubmit-Ready: Jason Macnak <natsu@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Jason Macnak <natsu@google.com>
Commit-Queue: Jason Macnak <natsu@google.com>