[nios2, committed] Fix PR80024

[Sandra Loosemore]

I've checked in this patch to fix a diagnostic message in the nios2 
backend.  This is in the target attribute parsing code; it now uses the 
same wording as the similar diagnostic for an incorrect value given to 
the corresponding command-line argument.

-Sandra

2018-10-27  Sandra Loosemore  <san...@codesourcery.com>

        PR target/80024

        gcc/
        * config/nios2/nios2.c (nios2_valid_target_attribute_rec): Fix
        error message.

Index: gcc/config/nios2/nios2.c
===================================================================
--- gcc/config/nios2/nios2.c	(revision 265560)
+++ gcc/config/nios2/nios2.c	(working copy)
@@ -4264,8 +4264,8 @@ nios2_valid_target_attribute_rec (tree a
 			    continue;
 			  if (!ISDIGIT (*t))
 			    {			 
-			      error ("`custom-%s=' argument requires "
-				     "numeric digits", N2FPU_NAME (code));
+			      error ("%<custom-%s=%> argument should be "
+				     "a non-negative integer", N2FPU_NAME (code));
 			      return false;
 			    }
 			}