dhrystone: Prevent procedure merging

Summary

From the Dhrystone RATIONAL file:

o No procedure merging

  Although Dhrystone contains some very short procedures where execution would
  benefit  from  procedure  merging (inlining, macro expansion of procedures),
  procedure merging is not to be used.  The reason is that the  percentage  of
  procedure  and  function  calls  is  part of the "Dhrystone distribution" of
  statements contained in [1].  This restriction does not hold for the  string
  functions  of  the  C  version  since ANSI C allows an implementation to use
  inline code for these functions.

We have to add -fno-inline to the CFLAGS.