This makes the test introduced in 537f5483fe4e more robust with respect
to the actual version number. The previous regex restricted the version
to start with a leading 1 which was overly restrictive.
I'd suggest overridding the version field with getenv("LLD_VERSION"). See ELF/SyntheticSections.cpp:getVersion.
A mechanism allowing easy cross-version comparison is useful.
If we override the behavior with an environment variable, the lit substitution can be removed.