Merge #17634: qt: Fix comparison function signature

98fbd1cdffaa69357091cc67e959ac21119dfa16 Use correct C++11 header for std::swap() (Hennadii Stepanov)
b66861e2e5e8a49e11e7489cf22c3007bc7082cc Fix comparison function signature (Hennadii Stepanov)

Pull request description:

  This PR fixes build on CentOS 7 with GCC 4.8.5:

  ```
  ...
  In file included from /usr/include/c++/4.8.2/algorithm:62:0,
                   from ./serialize.h:11,
                   from ./qt/sendcoinsrecipient.h:13,
                   from ./qt/recentrequeststablemodel.h:8,
                   from qt/recentrequeststablemodel.cpp:5:
  /usr/include/c++/4.8.2/bits/stl_algo.h: In instantiation of ‘_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&, _Compare) [with _RandomAccessIterator = QList<RecentRequestEntry>::iterator; _Tp = RecentRequestEntry; _Compare = RecentRequestEntryLessThan]’:
  /usr/include/c++/4.8.2/bits/stl_algo.h:2296:78:   required from ‘_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = QList<RecentRequestEntry>::iterator; _Compare = RecentRequestEntryLessThan]’
  /usr/include/c++/4.8.2/bits/stl_algo.h:2337:62:   required from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = QList<RecentRequestEntry>::iterator; _Size = int; _Compare = RecentRequestEntryLessThan]’
  /usr/include/c++/4.8.2/bits/stl_algo.h:5499:44:   required from ‘void std::sort(_RAIter, _RAIter, _Compare) [with _RAIter = QList<RecentRequestEntry>::iterator; _Compare = RecentRequestEntryLessThan]’
  qt/recentrequeststablemodel.cpp:208:82:   required from here
  /usr/include/c++/4.8.2/bits/stl_algo.h:2263:35: error: no match for call to ‘(RecentRequestEntryLessThan) (RecentRequestEntry&, const RecentRequestEntry&)’
      while (__comp(*__first, __pivot))
                                     ^
  In file included from qt/recentrequeststablemodel.cpp:5:0:
  ./qt/recentrequeststablemodel.h:43:7: note: candidate is:
   class RecentRequestEntryLessThan
         ^
  qt/recentrequeststablemodel.cpp:217:6: note: bool RecentRequestEntryLessThan::operator()(RecentRequestEntry&, RecentRequestEntry&) const
   bool RecentRequestEntryLessThan::operator()(RecentRequestEntry &left, RecentRequestEntry &right) const
        ^
  qt/recentrequeststablemodel.cpp:217:6: note:   no known conversion for argument 2 from ‘const RecentRequestEntry’ to ‘RecentRequestEntry&’
  In file included from /usr/include/c++/4.8.2/algorithm:62:0,
                   from ./serialize.h:11,
                   from ./qt/sendcoinsrecipient.h:13,
                   from ./qt/recentrequeststablemodel.h:8,
                   from qt/recentrequeststablemodel.cpp:5:
  /usr/include/c++/4.8.2/bits/stl_algo.h:2266:34: error: no match for call to ‘(RecentRequestEntryLessThan) (const RecentRequestEntry&, RecentRequestEntry&)’
      while (__comp(__pivot, *__last))
                                    ^
  In file included from qt/recentrequeststablemodel.cpp:5:0:
  ./qt/recentrequeststablemodel.h:43:7: note: candidate is:
   class RecentRequestEntryLessThan
         ^
  qt/recentrequeststablemodel.cpp:217:6: note: bool RecentRequestEntryLessThan::operator()(RecentRequestEntry&, RecentRequestEntry&) const
   bool RecentRequestEntryLessThan::operator()(RecentRequestEntry &left, RecentRequestEntry &right) const
        ^
  qt/recentrequeststablemodel.cpp:217:6: note:   no known conversion for argument 1 from ‘const RecentRequestEntry’ to ‘RecentRequestEntry&’
    CXX      qt/qt_libbitcoinqt_a-sendcoinsentry.o
  make[2]: *** [qt/qt_libbitcoinqt_a-recentrequeststablemodel.o] Error 1
  ```

  Also for `std::swap()` header `<algorithm>` is replaced with `<utility>` one.
  Refs:
  - [`std::swap()`](https://en.cppreference.com/w/cpp/algorithm/swap)
  - [standard library header `<utility>`](https://en.cppreference.com/w/cpp/header/utility)

ACKs for top commit:
  promag:
    Code review ACK 98fbd1cdffaa69357091cc67e959ac21119dfa16.
  jonasschnelli:
    utACK 98fbd1cdffaa69357091cc67e959ac21119dfa16
  fanquake:
    ACK 98fbd1cdffaa69357091cc67e959ac21119dfa16

Tree-SHA512: 91324490c1bdb98f186d233418e7e72ae7bee507876e94fb8c038bee031cea9e1046900f21156da4b7c33abcd726796867b124c4132d9ae3759877e90a8527db

1 files changed, 1 insertions, 1 deletions

diff --git a/src/qt/recentrequeststablemodel.h b/src/qt/recentrequeststablemodel.h
index 30578b7a03..f5085f7268 100644
--- a/src/qt/recentrequeststablemodel.h
+++ b/src/qt/recentrequeststablemodel.h
@@ -45,7 +45,7 @@ class RecentRequestEntryLessThan
 public:
     RecentRequestEntryLessThan(int nColumn, Qt::SortOrder fOrder):
         column(nColumn), order(fOrder) {}
-    bool operator()(RecentRequestEntry &left, RecentRequestEntry &right) const;
+    bool operator()(const RecentRequestEntry& left, const RecentRequestEntry& right) const;
 
 private:
     int column;