Fix makefile typo. Change-Id: I4f610396af2d31792d9b9e452abd8ac597eb1aee Reviewed-on: https://swiftshader-review.googlesource.com/4011 Reviewed-by: Greg Hartman <ghartman@google.com> Tested-by: Greg Hartman <ghartman@google.com> Reviewed-by: Nicolas Capens <capn@google.com>