analyzer: presize m_cluster_map in store copy ctor

analyzer: presize m_cluster_map in store copy ctor

Testing cc1 on pr93032-mztools-unsigned-char.c

Benchmark #1: (without patch)
  Time (mean ± σ):     338.8 ms ±  13.6 ms    [User: 323.2 ms, System: 14.2 ms]
  Range (min … max):   326.7 ms … 363.1 ms    10 runs

Benchmark #2: (with patch)
  Time (mean ± σ):     332.3 ms ±  12.8 ms    [User: 316.6 ms, System: 14.3 ms]
  Range (min … max):   322.5 ms … 357.4 ms    10 runs

Summary
  ./cc1.new ran 1.02 ± 0.06 times faster than ./cc1.old

gcc/analyzer/ChangeLog:
	* store.cc (store::store): Presize m_cluster_map.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>