Thread: pgsql-server: Document what the "rep; nop" x86 assembler sequence is

Log Message:
-----------
Document what the "rep; nop" x86 assembler sequence is actually equivalent
to, and what it is intended to do.

Modified Files:
--------------
    pgsql-server/src/include/storage:
        s_lock.h (r1.131 -> r1.132)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/storage/s_lock.h.diff?r1=1.131&r2=1.132)