Fix GCC -Wsuggest-paranthesis

Author: mborland

include/boost/int128/numeric.hpp

@@ -284,7 +284,7 @@ constexpr uint128_t gcd(uint128_t a, uint128_t b) noexcept
 constexpr int128_t gcd(const int128_t a, const int128_t b) noexcept
 {
     const auto res {static_cast<int128_t>(gcd(static_cast<uint128_t>(abs(a)), static_cast<uint128_t>(abs(b))))};
-    return a < 0 != b < 0 ? -res : res;
+    return (a < 0) != (b < 0) ? -res : res;
 }
 
 constexpr uint128_t lcm(const uint128_t a, const uint128_t b) noexcept
@@ -304,7 +304,7 @@ constexpr uint128_t lcm(const uint128_t a, const uint128_t b) noexcept
 constexpr int128_t lcm(const int128_t a, const int128_t b) noexcept
 {
     const auto res {static_cast<int128_t>(lcm(static_cast<uint128_t>(abs(a)), static_cast<uint128_t>(abs(b))))};
-    return a < 0 != b < 0 ? -res : res;
+    return (a < 0) != (b < 0) ? -res : res;
 }
 
 } // namespace int128