Downloaded from http://ftp.gnu.org/gnu/sed/ and extracted verbatim.

Needed to build Mac GCCs for mips/mips64 --- the BSD sed doesn't
supported extended regex alternate syntax \(a\|b\). It will understand
sed -E "(a|b)" with the escapes removed, but that's not what's in the
configure file.

Bug: http://b/22099482
Change-Id: Iec036ab35497a957fe462de1d4fdc326e7df5844