Check inside the deserializer that const atoms are indeed const, don't
trust the input. The serializer only writes type 0 records for const
atoms but the byte stream may have been corrupted or manipulated.
Overlooked during review of c25aad7 ("Add ability to (de)serialize
symbols")
Found with libfuzzer and it found it _really_ fast. Great tool.
* Add utility functions, improve integer conversion functions
- move `is_be()` to cutils.h
- add `is_upper_ascii()` and `to_upper_ascii()`
- add extensive benchmark for integer conversion variants in **tests/test_conv.c**
- add `u32toa()`, `i32toa()`, `u64toa()`, `i64toa()` based on register shift variant
- add `u32toa_radix()`, `u64toa_radix()`, `i64toa_radix()` based on length_loop variant
- use direct converters instead of `snprintf()`
- copy NaN and Infinity directly in `js_dtoa1()`
- optimize `js_number_toString()` for small integers
- use `JS_NewStringLen()` instead of `JS_NewString()` when possible
- add more precise conversion tests in microbench.js
- disable some benchmark tests for gcc (they cause ASAN failures)
- `-s` strips the source code
- `-ss` strips source and line/column numbers information
- `qjsc repl.js` generates an object size of **105726** bytes
- `qjsc -s repl.js` generates an object size of **20853** bytes
- `qjsc -ss repl.js` generates an object size of only **16147** bytes
- compile repl.js with `-ss`
- bump byte code version to 12
