Better comment than what was submitted in r28614.

This commit was SVN r28631.

The following SVN revision numbers were found above:
  r28614 --> open-mpi/ompi@9556310bd0

ompi/mca/btl/openib/btl_openib_component.c

@@ -39,11 +39,16 @@
 #include <stddef.h>
 #if BTL_OPENIB_MALLOC_HOOKS_ENABLED
 /*
- * The include of malloc.h below breaks layers in OMPI
- * The malloc hooks in newer glibc were deprecated, including stock malloc.h causes compilation erros
- * So, we use internal malloc.h which does not cause compilation errors.
- * Internally, OMPI uses built-in ptmalloc anyway
+ * The include of malloc.h below breaks abstractions in OMPI (by
+ * directly including a header file from another component), but has
+ * been ruled "ok" because the openib component is only supported on
+ * Linux.  
  *
+ * The malloc hooks in newer glibc were deprecated, including stock
+ * malloc.h causes compilation warnings.  Instead, we use the internal
+ * linux component malloc.h which does not cause these warnings.
+ * Internally, OMPI uses the built-in ptmalloc from the linux memory
+ * component anyway.
  */
 #include "opal/mca/memory/linux/malloc.h"
 #endif