C++ 11 is in heavy use by SwiftShader now, so SwiftShader is now unsupported for Android versions earlier than M.

Bug: b/130460252
Bug: b/130343040
Bug: b/130361288
Change-Id: Idfb64c3fa82325641cc2170f494260c1b5b1eeb4
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/28988Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: Lingfeng Yang <lfy@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>