aarch64: Eliminate unused variable warnings with -DNDEBUG

opcodes/aarch64-asm.c

diff --git a/opcodes/aarch64-asm.c b/opcodes/aarch64-asm.c
index 565c4b1..29e96e2 100644
--- a/opcodes/aarch64-asm.c
+++ b/opcodes/aarch64-asm.c
@@ -1325,7 +1325,7 @@
 				   ATTRIBUTE_UNUSED)
 {
   unsigned int num_regs = get_operand_specific_data (self);
-  unsigned int mask = 16 | (16 / num_regs - 1);
+  unsigned int mask ATTRIBUTE_UNUSED = 16 | (16 / num_regs - 1);
   unsigned int val = info->reglist.first_regno;
   assert ((val & mask) == val);
   insert_field (self->fields[0], code, val >> 4, 0);

opcodes/aarch64-dis.c

diff --git a/opcodes/aarch64-dis.c b/opcodes/aarch64-dis.c
index f63b747..82d2f8f 100644
--- a/opcodes/aarch64-dis.c
+++ b/opcodes/aarch64-dis.c
@@ -3686,8 +3686,9 @@
 
       for (i = 0; i <= 0xf; ++i)
 	{
-	  int res = snprintf (&formats[i][0], sizeof (formats[i]), "%c%x%c",
-			      STYLE_MARKER_CHAR, i, STYLE_MARKER_CHAR);
+	  int res ATTRIBUTE_UNUSED
+	    = snprintf (&formats[i][0], sizeof (formats[i]), "%c%x%c",
+			STYLE_MARKER_CHAR, i, STYLE_MARKER_CHAR);
 	  assert (res == 3);
 	}
 

opcodes/aarch64-opc.c

diff --git a/opcodes/aarch64-opc.c b/opcodes/aarch64-opc.c
index 5b76f2c..965c1c0 100644
--- a/opcodes/aarch64-opc.c
+++ b/opcodes/aarch64-opc.c
@@ -3335,12 +3335,11 @@
 	       invalid tying and invalid qualifiers, the error about
 	       qualifiers would suggest several alternative instructions
 	       that also have invalid tying.  */
-	    enum aarch64_operand_class op_class1
+	    enum aarch64_operand_class op_class
 	       = aarch64_get_operand_class (inst->operands[0].type);
-	    enum aarch64_operand_class op_class2
-	       = aarch64_get_operand_class (inst->operands[i].type);
-	    assert (op_class1 == op_class2);
-	    if (op_class1 == AARCH64_OPND_CLASS_SVE_REGLIST
+	    assert (aarch64_get_operand_class (inst->operands[i].type)
+		    == op_class);
+	    if (op_class == AARCH64_OPND_CLASS_SVE_REGLIST
 		? ((inst->operands[0].reglist.first_regno
 		    != inst->operands[i].reglist.first_regno)
 		   || (inst->operands[0].reglist.num_regs