OS-4368 lxbrand glibc abhors CPUID limits

*** 39,48 ****
--- 39,53 ----
  
         See the processor manufacturers documentation for further information
         about the syntax and semantics of the wide variety of information
         available from this instruction.
  
+        Some systems can be configured to limit the cpuid opcodes which are
+        accessible.  While illumos handles this condition, other software may
+        malfunction when such limits are enabled.  Those settings are typically
+        manipulated in the BIOS.
+ 
  EXAMPLE
         This example allows you to determine if the current x86 processor
         supports "long mode," which is a necessary (but not sufficient)
         condition for running the 64-bit Solaris kernel on the processor.