added IDataType::updateAvgValueSizeHints; renamed PODArray::allocated_size to PODArray::allocated_bytes; renamed renamed IColumn::allocatedSize to IColumn::allocatedBytes; removed IColumn.h from IDataType.h

Output format json quote denormals

Fix system libunwind test

disabled check for settings with same value in readonly mode in InterpreterSetQuery [#CLICKHOUSE-3041]; added tests for output_format_json_quote_denormals setting

`unw_init_local_signal` is provided as:

- `_ULx86_64_init_local_signal` in `libunwind`
- `_Ux86_64_init_local_signal` in `libunwind-generic`

`find_library (UNWIND_LIBRARY unwind)` looks for the first library;
`#define UNW_LOCAL_ONLY` before `#include <libunwind.h>` is necessary to select
this variant.