Missing pointer dereference in tree-affine.c

wide_int_constant_multiple_p used:

          if (*mult_set && mult != 0)
            return false;

to check whether we had previously seen a nonzero multiple, but "mult" is
a pointer to the previous value rather than the previous value itself.

Noticed by inspection while working on another patch, so I don't have a
testcase.  I tried adding an assert for combinations that were wrongly
rejected before but it didn't trigger during a bootstrap and regtest.

Tested on x86_64-linux-gnu.

gcc/
	* tree-affine.c (wide_int_constant_multiple_p): Add missing
	pointer dereference.

From-SVN: r236040

gcc/ChangeLog

+2016-05-09  Richard Sandiford  <richard.sandiford@arm.com>
+
+	* tree-affine.c (wide_int_constant_multiple_p): Add missing
+	pointer dereference.
+
 2016-05-09  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/70985

gcc/tree-affine.c

@@ -769,7 +769,7 @@ wide_int_constant_multiple_p (const widest_int &val, const widest_int &div,
 
   if (val == 0)
     {
-      if (*mult_set && mult != 0)
+      if (*mult_set && *mult != 0)
 	return false;
       *mult_set = true;
       *mult = 0;