Merge pull request #9810 from jsquyres/pr/v4.1.x/heterogeneous-functionality-is-broken

v4.1.x: README: update --enable-heterogeneous warning

Author: bwbarrett

README

@@ -1533,11 +1533,11 @@ MISCELLANEOUS FUNCTIONALITY
   with different endian representations).  Heterogeneous support is
   disabled by default because it imposes a minor performance penalty.
 
+  *** THE HETEROGENEOUS FUNCTIONALITY IS CURRENTLY BROKEN - DO NOT USE ***
+
  --enable-spc
   Enable software-based performance counters capability.
 
-  *** THIS FUNCTIONALITY IS CURRENTLY BROKEN - DO NOT USE ***
-
 --with-wrapper-cflags=<cflags>
 --with-wrapper-cxxflags=<cxxflags>
 --with-wrapper-fflags=<fflags>