std.cfg: Added support for std::tmpfile() (danmar#7162)

Reference: https://en.cppreference.com/w/cpp/io/c/tmpfile

Author: orbitcowboy

cfg/std.cfg

@@ -5669,6 +5669,13 @@ The obsolete function 'gets' is called. With 'gets' you'll get a buffer overrun
     <returnValue type="FILE *"/>
     <noreturn>false</noreturn>
   </function>
+  <!-- FILE *std::tmpfile(void); -->
+  <!-- https://en.cppreference.com/w/cpp/io/c/tmpfile -->
+  <function name="std::tmpfile">
+    <use-retval/>
+    <returnValue type="std::FILE *"/>
+    <noreturn>false</noreturn>
+  </function>
   <!-- int tolower(int c); -->
   <function name="tolower,std::tolower">
     <pure/>