top: use CPU_ZEROTICS to embrace the Nehalem logic

The recently added logic dealing with "missing" tics
is mutually exclusive with logic associated with a
define called CPU_ZEROTICS.

This commit expands the use of that define to exclude
such Nehalem logic as appropriate.

It also extends programmer notes in top.h to include
an attribution for initiating the topic of potential
Nehalem type % CPU distortions, acknowledging:
  Jaromir Capik, <jcapik@redhat.com>

References
commit ce1410a51a
commit 9e7dd43ab7
commit a9041a5526

top/top.h

@@ -56,12 +56,16 @@
               Jan Gorig <jgorig@redhat.com> - April, 2011 */
 
         /* For the motivation and path to nls support, thanks to:
-              Sami Kerola, <kerolasa@iki.fi> */
+              Sami Kerola, <kerolasa@iki.fi> - December, 2011 */
 
         /* There are still some short strings that may yet be candidates
            for nls support inclusion.  They're identified with:
               // nls_maybe */
 
+        /* For initiating the topic of potential % CPU distortions due
+           to Nehalem type processors (see CPU_ZEROTICS), thanks to:
+               Jaromir Capik, <jcapik@redhat.com> - February, 2012 */
+
 #ifdef PRETEND2_5_X
 #define linux_version_code LINUX_VERSION(2,5,43)
 #endif
@@ -225,7 +229,9 @@ typedef struct CT_t {
 typedef struct CPU_t {
    CT_t cur;                      // current frame's cpu tics
    CT_t sav;                      // prior frame's cpu tics
+#ifndef CPU_ZEROTICS
    SIC_t edge;                    // tics adjustment threshold boundary
+#endif
    int id;                        // the cpu id number (0 - nn)
 } CPU_t;