Emit a symbol table entry for each function we output to the ELF file. This

allows objdump to know which function we are emitting to:

00000000 <foo>:     <----
   0:   b8 01 00 00 00          mov    $0x1,%eax
   5:   03 44 24 04             add    0x4(%esp,1),%eax
   9:   c3                      ret

... and allows .o files to be useful for linking :)

llvm-svn: 22378