Find tcmalloc library using the cmake find_library() feature.
Find tcmalloc library using the cmake find_library() feature.

This hopefully makes it more reliably compile in some
environments (e.g. currently in building the conda packages we
have to switch off the tcmalloc feature because it doesn't build
there).

Signed-off-by: Henner Zeller <259ad50fabbfd39355f36ecd6c0afca541ea66ef@acm.org>

alainmarcel/Surelog,chipsalliance/Surelog,alainmarcel/Surelog,chipsalliance/Surelog,alainmarcel/Surelog,chipsalliance/Surelog,chipsalliance/Surelog,alainmarcel/Surelog