Add -ftrapv to DEBUG_CXXFLAGS when --enable-debug is used

Author: practicalswift

configure.ac

@@ -263,6 +263,7 @@ if test "x$enable_debug" = xyes; then
 
   AX_CHECK_PREPROC_FLAG([-DDEBUG],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG"]],,[[$CXXFLAG_WERROR]])
   AX_CHECK_PREPROC_FLAG([-DDEBUG_LOCKORDER],[[DEBUG_CPPFLAGS="$DEBUG_CPPFLAGS -DDEBUG_LOCKORDER"]],,[[$CXXFLAG_WERROR]])
+  AX_CHECK_COMPILE_FLAG([-ftrapv],[DEBUG_CXXFLAGS="$DEBUG_CXXFLAGS -ftrapv"],,[[$CXXFLAG_WERROR]])
 fi
 
 if test x$use_sanitizers != x; then