Fix a memory leak on topology_parse().

[araujo]

Summary

strdup(3) allocates memory for a copy of the string, does the copy and returns a pointer to it. If there is no sufficient memory NULL is returned and the global errno is set to ENOMEM. We do a sanity check to see if it was possible to allocate enough memory.

Also as we allocate memory, we need to free this memory used. OR it will going out of scope leaks the storage it points to.

Test Plan

smoke tests using clang and gcc47.

[rgrimes]

Please mark the commit as MFC-X with https://svnweb.freebsd.org/changeset/base/332298

[araujo]

In D15550#328333, @rgrimes wrote:

Please mark the commit as MFC-X with https://svnweb.freebsd.org/changeset/base/332298

Hi,

Isn't it X-MFC? I got confused after see another review related with MFC after and before! But I'm almost sure it is X-MFC.

Best,