posix.cfg: Added support for dlerror() (danmar#7150)

Reference: https://www.man7.org/linux/man-pages/man3/dlerror.3.html

Author: orbitcowboy

cfg/posix.cfg

@@ -511,6 +511,13 @@
       <not-uninit/>
     </arg>
   </function>
+  <!-- see https://www.man7.org/linux/man-pages/man3/dlerror.3.html -->
+  <!-- char *dlerror(void); -->
+  <function name="dlerror">
+    <noreturn>false</noreturn>
+    <use-retval/>
+    <returnValue type="char*"/>
+  </function>
   <!-- see http://pubs.opengroup.org/onlinepubs/9699919799/functions/dlopen.html -->
   <!-- void *dlopen(const char *file, int mode); -->
   <function name="dlopen">