Remove unnecessary defines/undefines in the makefiles

The following defines aren't referenced anywhere in the code base:

The DEFAULT_ARCH define isn't used within the encoder at all.

The ANDROID define isn't referenced anywhere either, and if necessary,
the automatically enabled define __ANDROID__ can be used instead.

The defines INSERT_LOGO and LOGO_EN were undefined in the makefiles,
but that is unnecessary since nothing actually defines them. The
decoder x86_64 makefile also undefined LOGO_EN; an architecture
specific makefile shouldn't touch such feature settings, otherwise
there's a risk that different builds for different architectures
behave significantly differently.

Change-Id: I13b86c8bf2feb3a381d904a13f18c3b35f40a575
9 files changed