Rather than specifying defines using explicit commands in "cflags"
sections, all defines were moved to generic "defines" sections.

Change-Id: Ica6ee2a2447aae4f8fc6decc3a4f6b40af7ce9fd
Reviewed-on: https://swiftshader-review.googlesource.com/8948Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>