Revert "Spawn gdb to get backtrace of all threads on assert (Linux only)"
Revert "Spawn gdb to get backtrace of all threads on assert (Linux only)"

A more robust crash catching mechanism (using Breakpad) will replace
it.

This reverts commit bda6f4266cc36ca3b387e410d9add1b91484f5ba.

couchbase/forestdb,sushmaad/forestdb,wurikiji/forestdb,zhaog/forestdb,sushmaad/forestdb,wurikiji/forestdb,joliss/forestdb,zhaog/forestdb,joliss/forestdb,hisundar/forestdb,hisundar/forestdb,couchbase/forestdb