bitfields of size 1 should be unsigned if 1 is stored there

[r6556]

ir/ir/irarch.h

@@ -18,15 +18,15 @@
  */
 typedef struct {
   /* Mul optimization */
-  int also_use_subs : 1;                /**< Use also Subs when resolving Muls to shifts */
+  unsigned also_use_subs : 1;           /**< Use also Subs when resolving Muls to shifts */
   int maximum_shifts;                   /**< The maximum number of shifts that shall be inserted for a mul. */
   unsigned highest_shift_amount;        /**< The highest shift amount you want to
 			                     tolerate. Muls which would require a higher
 			                     shift constant are left. */
 
   /* Div/Mod optimization */
-  int allow_mulhs   : 1;        /**< Use the Mulhs operation for division by constant */
-  int allow_mulhu   : 1;        /**< Use the Mulhu operation for division by constant */
+  unsigned allow_mulhs   : 1;   /**< Use the Mulhs operation for division by constant */
+  unsigned allow_mulhu   : 1;   /**< Use the Mulhu operation for division by constant */
   int max_bits_for_mulh;        /**< Maximum number of bits the Mulh operation can take.
                                      Modes with higher amount of bits will use Mulh */
 } arch_dep_params_t;