Use interned strings in mvc/model/query.c

[ghost]

Memory usage as reported by valgrind:

• Before: total heap usage: 167,926 allocs, 97,608,376 bytes allocated
• After: total heap usage: 167,095 allocs, 97,550,362 bytes allocated

Memory usage via memory_get_usage() (real / PHP):

• before: (4194304) (4699096)
• after: (3932160) (4639400)

Tested with:

• USE_ZEND_ALLOC=0 valgrind $(phpenv which php) unit-tests/manual-unit.php ModelsQueryParsingTest.php ModelsQueryParsingTest
• $(phpenv which php) unit-tests/manual-unit.php ModelsQueryParsingTest.php ModelsQueryParsingTest

The goal was to see how viable this optimization is — I did not try to replace all strings with interned ones.

[ghost]

6aa5f41, 058d023 and 9ae48e7 add support for interned strings to PHQL parser.

total heap usage: 167,096 allocs, 97,528,018 bytes allocated

22K memory saved :-)