gcc 4.8 vs i386 non-DIAGNOSTIC kernels

["John D. Baker" <jdbaker%mylinuxisp.com@localhost>]

For those trying gcc 4.8 with port-i386, or working to prepare it for
the switch, non-DIAGNOSTIC kernels such as NET4501 incur "set-but-not-used"
warning/failure.  The following change (as gleaned from amd64/trap.c)
allows the build to proceed:

+Index: sys/arch/i386/i386/trap.c
+===================================================================
+RCS file: /cvsroot/src/sys/arch/i386/i386/trap.c,v
+retrieving revision 1.271
+diff -u -b -r1.271 trap.c
+--- sys/arch/i386/i386/trap.c  12 Feb 2014 23:24:09 -0000      1.271
++++ sys/arch/i386/i386/trap.c  12 Mar 2014 15:06:43 -0000
+@@ -747,7 +747,7 @@
+ {
+       ucontext_t *uc = arg;
+       lwp_t *l = curlwp;
+-      int error;
++      int error __diagused;
+ 
+ 	error = cpu_setmcontext(l, &uc->uc_mcontext, uc->uc_flags);
+       KASSERT(error == 0);

--
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