E is usually defined as a shorthand for AV_OPT_FLAG_ENCODING_PARAM.
Rename the single expansion E(x) now used in libavutil to E1.

This is what the OpenBSD porter's manual describes as correct, cf.
http://www.openbsd.org/faq/ports/specialtopics.html#SharedLibs

This allows employing that number in library install commands.