gdbserver: Check r_version < 1 for Linux debugger interface

gdbserver: Check r_version < 1 for Linux debugger interface

Update gdbserver to check r_version < 1 instead of r_version != 1 so
that r_version can be bumped for a new field in the glibc debugger
interface to support multiple namespaces.  Since so far, the gdbserver
only reads fields defined for r_version == 1, it is compatible with
r_version >= 1.

All future glibc debugger interface changes will be backward compatible.
If there is ever the need for backward incompatible change to the glibc
debugger interface, a new DT_XXX element will be provided to access the
new incompatible interface.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=11839