Improve std.cfg: std::addressof(), std::stringstream::str() (#4710)

* Improve std.cfg: std::addressof(), std::stringstream::str()

* Format

* Add <leak-ignore/>

Author: chrchr-github

cfg/std.cfg

@@ -6426,6 +6426,13 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     <leak-ignore/>
     <arg nr="any"/>
   </function>
+  <!-- std::basic_string<CharT,Traits,Allocator> str() const; -->
+  <!-- void str( const std::basic_string<CharT,Traits,Allocator>& s ); -->
+  <function name="std::stringstream::str,std::istringstream::str,std::ostringstream::str">
+    <noreturn>false</noreturn>
+    <leak-ignore/>
+    <arg nr="any"/>
+  </function>
   <!-- /*unspecified*/ setbase(int base); -->
   <function name="setbase,std::setbase">
     <noreturn>false</noreturn>
@@ -6764,6 +6771,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
   <!-- template< class T2, std::size_t N > void swap( T2 (&a)[N], T2 (&b)[N]) -->
   <!-- template< class T2, std::size_t N > constexpr void swap( T2 (&a)[N], T2 (&b)[N]) -->
   <function name="std::swap">
+    <leak-ignore/>
     <noreturn>false</noreturn>
     <returnValue type="void"/>
     <arg nr="1">
@@ -6773,6 +6781,16 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
       <not-uninit/>
     </arg>
   </function>
+  <!-- https://en.cppreference.com/w/cpp/memory/addressof -->
+  <!-- template< class T > constexpr T* addressof( T& arg ) noexcept; -->
+  <function name="std::addressof">
+    <leak-ignore/>
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <returnValue type="void*">&amp; arg1</returnValue>
+    <arg nr="1">
+    </arg>
+  </function>
   <function name="std::stack::pop,std::queue::pop">
     <noreturn>false</noreturn>
   </function>

test/cfg/std.cpp

@@ -4550,3 +4550,9 @@ class A
         for (std::vector<std::string>::reverse_iterator it = m_str.rbegin(); it != m_str.rend(); ++it) {;}
     }
 };
+
+void addressof(int a)
+{
+    // cppcheck-suppress ignoredReturnValue
+    std::addressof(a);
+}