build: notcmalloc builds enable WITH_BOOST_VALGRIND

build: notcmalloc builds enable WITH_BOOST_VALGRIND

this flag silences a false-positive from valgrind in boost::context:
```
<error>
  <unique>0x0</unique>
  <tid>124</tid>
  <kind>InvalidRead</kind>
  <what>Invalid read of size 8</what>
  <stack>
    <frame>
      <ip>0x52FF7E7</ip>
      <obj>/usr/lib64/libradosgw.so.2.0.0</obj>
      <fn>spawn::detail::continuation_context::resume()</fn>
    </frame>
  </stack>
  <auxwhat>Address 0x57f65728 is in a rw- anonymous segment</auxwhat>
</error>
```

Fixes: https://tracker.ceph.com/issues/48963
Signed-off-by: Casey Bodley <cbodley@redhat.com>