Bumped to alpha2 -- fix dependencies for amd64

The 7.7.3_alpha2 ebuild no longer is no longer keyworded to be available
to amd64. This is a temporary problem because the test tarball released
by Logitech does not include any binaries for amd64 for the 5.16 Perl
arch. I expect that will be fixed when a full Perl-5.16-compatible
version is released.
Official 7.7.3 release from upstream (Logitech)

This release supports Perl 5.16 on x86, but only 5.14 or earlier on
amd64 due to Logitech not yet releasing the bundled binaries for 64bit
Perl 5.16.
Merge branch 'release/7.7.3'
Merge tag '7.7.3' into develop

Upstream 7.7.3 release