Revert "elfread.c (elf_symtab_read): Stop memory leak"

Revert "elfread.c (elf_symtab_read): Stop memory leak"

It turns out that this change is not correct, and it causes a crash
on sparc-solaris while trying to load ld.so.  This is because the
memory is actually still referenced after elf_symtab_read completes.

gdb/ChangeLog:

        * elfread.c (elf_symtab_read): Revert the previous change
        that tried to stop a memory leak.