chore(php-shim): drop the HHVM_VERSION constant

The constant was None and defined("HHVM_VERSION") reports it undefined, so
every branch guarded by it was dead: shirabe is a Rust binary and never runs
on HHVM. HhvmDetector keeps probing for an `hhvm` binary in PATH, which is
what actually produces the hhvm platform package.

Two of the dropped branches ask about the PHP runtime that consumes the
result rather than about shirabe itself -- the class loader's Hack file
lookup and the class map parser's enum scanning -- so both get a
TODO(php-runtime) marker.

0 files changed, 0 insertions, 0 deletions