Description of problem:
calling dwfl_module_addrname on a symbol with a st_size of 0 returns null when
it should return the symbol size.

Version-Release number of selected component (if applicable):
0.125

How reproducible:
always.

Steps to Reproduce:
1. Create assembly test with code for a function with no symbol size. That
segfaults.
2. Run the program and try to get a backtrace using dwfl_module_addrname.
  
Actual results:
Get null.

Expected results:
Get foo().

Additional info:
Check out the patch for a possible solution.