Fix cfg for std::xstream::write() (#4778)

Author: chrchr-github

cfg/std.cfg

@@ -6539,7 +6539,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
-      <valid>1:</valid>
+      <valid>0:</valid>
     </arg>
   </function>
   <!--std::ostringstream& std::ostringstream::write (const char* s, streamsize n);-->
@@ -6554,7 +6554,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
-      <valid>1:</valid>
+      <valid>0:</valid>
     </arg>
   </function>
   <!--std::ostream& std::ostream::write (const char* s, streamsize n);-->
@@ -6569,7 +6569,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
-      <valid>1:</valid>
+      <valid>0:</valid>
     </arg>
   </function>
   <!--std::fstream& std::fstream::write (const char* s, streamsize n);-->
@@ -6584,7 +6584,7 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     </arg>
     <arg nr="2" direction="in">
       <not-uninit/>
-      <valid>1:</valid>
+      <valid>0:</valid>
     </arg>
   </function>
   <!-- void std::vector::assign( size_type count, const T& value ); -->

test/cfg/std.cpp

@@ -4458,6 +4458,11 @@ void getline()
     in.close();
 }
 
+void stream_write(std::ofstream& s, std::vector<char> v) {
+    if (v.empty()) {}
+    s.write(v.data(), v.size());
+}
+
 void stdstring()
 {
     std::string s;