Fix ASAN build
Fix ASAN build

ASAN builds do not use tcmalloc and therefore should not try to load the
extensions provided by tcmalloc.

Change-Id: I3aa3346172068a2127adad0bd14aed854f9e79f6
Reviewed-on: http://gerrit.cloudera.org:8080/387
Reviewed-by: Ippokratis Pandis <49df5a81b84182d67af5e425b1c52ae595fc1f17@cloudera.com>
Reviewed-by: Alex Behm <fe1626037acfc2dc542d2aa723a6d14f2464a20c@cloudera.com>
Tested-by: Internal Jenkins

cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala