Mark DriverRec exported in atimach64probe.h to match atimach64probe.c
Fixes build failure when compiling with Solaris Studio compiler
using -xldscope=hidden
:
"atimach64probe.c", line 308: redeclaration must have the same or more restrictive linker scoping: MACH64
[Upstreaming patch Solaris has been carrying locally since 2015.]