Merge bitcoin/bitcoin#24395: build: use `BOOST_MULTI_INDEX_ENABLE_SAFE_MODE` when debugging

06e18e0b53 build: use BOOST_MULTI_INDEX_ENABLE_SAFE_MODE when debugging (fanquake)

Pull request description:

  Use of this macro enables precondition checks for iterators and functions of the library. It's use is recommended in debug builds. See https://www.boost.org/doc/libs/1_78_0/libs/multi_index/doc/tutorial/debug.html for more info.

  There is also a `BOOST_MULTI_INDEX_ENABLE_INVARIANT_CHECKING` macro:
  > When this mode is in effect, all public functions of Boost.MultiIndex will perform post-execution tests aimed at ensuring that the basic internal invariants of the data structures managed are preserved.

ACKs for top commit:
  laanwj:
    Concept and code review ACK 06e18e0b53

Tree-SHA512: 7ee489eccda81c7dbca9210af6d3007d5b2c704b645139d2714c077af157789dd9478c29d0d212e210e96686ea83713aaf3d458e879122b3cde64f3e3e3789d2

configure.ac

@@ -1454,6 +1454,10 @@ if test "$use_boost" = "yes"; then
   dnl we don't use multi_index serialization
   BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_MULTI_INDEX_DISABLE_SERIALIZATION"
 
+  if test "$enable_debug" = "yes" || test "$enable_fuzz" = "yes"; then
+    BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE"
+  fi
+
   if test "$suppress_external_warnings" != "no"; then
     BOOST_CPPFLAGS=SUPPRESS_WARNINGS($BOOST_CPPFLAGS)
   fi