- Had to rename .c of .c/.s pair to avoid Android's build system
  producing name clashes
- Rename .s to .S to get assembler-with-cpp behavior

Bug: b/139010488
Change-Id: Ib5ee9355e60fe52b1caedfc6ec1b456296d519f5
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/35188Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>