RFR 8219951: Build failure on Mac and Windows after JDK-8219922

[Vladimir Kozlov]

https://bugs.openjdk.java.net/browse/JDK-8219951

Add missing parentheses.

Tested tier1 (includes builds), hs-tier2

-- 
Thanks,
Vladimir

diff -r 86ee52ca11e3 src/hotspot/share/opto/indexSet.hpp
--- a/src/hotspot/share/opto/indexSet.hpp
+++ b/src/hotspot/share/opto/indexSet.hpp
@@ -440,7 +440,7 @@
      uint current = _current;
      if (current != 0) {
        uint advance = count_trailing_zeros(current);
-      assert((current >> advance) & 0x1 == 1, "sanity");
+      assert(((current >> advance) & 0x1) == 1, "sanity");
        _current = (current >> advance) - 1;
        _value += advance;
        return _value;