Fix bugs in analyze_empty_tables behavior

[aakash10292]

This patch fixes the following bugs in analyze_empty_tables behavior :
1.) stat4 is not populated for empty tables
2.) with this tunable on, a previously empty table which has rows inserted into it, does not have it's stat4 info updated when analyze runs on it.

ex:
The following script :

function purge_stats
{
    ${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "truncate sqlite_stat1"
    ${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "truncate sqlite_stat4"
}
function count_stats 
{
    ${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "select count(*) from sqlite_stat1"
    ${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "select count(*) from sqlite_stat4"
}

purge_stats
#default behavior
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "DROP TABLE IF EXISTS empty"
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "CREATE TABLE empty(a int primary key)"
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "ANALYZE empty"
count_stats

echo "TURNING ON ANALYZE EMPTY TABLES"
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "exec procedure sys.cmd.send('setsqlattr analyze_empty_tables on')"
purge_stats
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "ANALYZE empty"
count_stats

echo "INSERTING RECORDS"
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "INSERT INTO EMPTY SELECT * FROM generate_series(0,49999)"
echo "RUNNING ANALYZE"
purge_stats
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "ANALYZE empty"
count_stats

echo "TURNING OFF ANALYZE EMPTY TABLES"
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "exec procedure sys.cmd.send('setsqlattr analyze_empty_tables off')"
echo "RUNNING ANALYZE"
purge_stats
${CDB2SQL_EXE} ${CDB2_OPTIONS} ${DBNAME} local "ANALYZE empty"
count_stats

Produces :

(count(*)=0)
(count(*)=0)
TURNING ON ANALYZE EMPTY TABLES
(count(*)=1)
**(count(*)=0)**.  -> ISSUE 1
INSERTING RECORDS
(rows inserted=50000)
RUNNING ANALYZE
(count(*)=1)
**(count(*)=0)**  -> ISSUE 2
TURNING OFF ANALYZE EMPTY TABLES
RUNNING ANALYZE
(count(*)=1)
(count(*)=24)

Output with patch fix :

(count(*)=0)
(count(*)=0)
TURNING ON ANALYZE EMPTY TABLES
(count(*)=1)
(count(*)=1)
INSERTING RECORDS
(rows inserted=50000)
RUNNING ANALYZE
(count(*)=1)
(count(*)=24)
TURNING OFF ANALYZE EMPTY TABLES
RUNNING ANALYZE
(count(*)=1)
(count(*)=24)

[roborivers]

Coding style check: Success ✓.
Smoke testing: Success ✓.
Cbuild submission: Success ✓.
Regression testing: 225/591 tests failed ⚠.

The first 10 failing tests are:
sirandtest2 [setup failure]
sc_inserts_logicalsc_generated [setup failure]
selectv [setup failure]
rawindex [setup failure]
sc_truncate_lockorder_generated
phys_rep_perf
online_compaction
analyze_partial_index_off_generated
analyze
snap_ha_retry_newsi_generated

[roborivers]

Coding style check: Success ✓.
Smoke testing: Success ✓.
Cbuild submission: Success ✓.
Regression testing: 8/591 tests failed ⚠.

The first 10 failing tests are:
basic_rowset_generated [setup failure]
basic_rowlocks_generated [setup failure]
basic_nogenid48_generated [setup failure]
phys_rep_perf
comdb2sys_queueodh_generated
comdb2sys_pagesize_generated
comdb2sys
snap_ha_retry_newsi_generated