Sparc: comment out unused variable, spotted by clang

The variable is_annulled is referenced in a FIXME comment, so instead
of removing the variable, comment out the lines so that the FIXME
can be understood.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/sparc-dis.c b/sparc-dis.c
index 53c8c90..83a12ae 100644
--- a/sparc-dis.c
+++ b/sparc-dis.c
@@ -2760,7 +2760,7 @@
           int found_plus = 0;
 
           /* Nonzero means we have an annulled branch.  */
-          int is_annulled = 0;
+          /* int is_annulled = 0; */ /* see FIXME below */
 
           /* Do we have an `add' or `or' instruction combining an
              immediate with rs1?  */
@@ -2796,7 +2796,7 @@
                       {
                       case 'a':
                         (*info->fprintf_func) (stream, "a");
-                        is_annulled = 1;
+                        /* is_annulled = 1; */ /* see FIXME below */
                         ++s;
                         continue;
                       case 'N':