[lldb] Relax libc++ ABI version checking

libc++ has programmable ABI versioning controllable with the _LIBCPP_ABI_VERSION
macro.  Currently there are at least 3 settings used in real systems (1 as the
default, ndk1 for Anroid, Cr for Chromium).

Only the 1 and ndk1 cases were handled.  This change relaxes the check to allow
any ABI version.

Differential Revision: https://reviews.llvm.org/D57466

llvm-svn: 352899