Port bellard/quickjs "dtoa library" commits

[past-due]

Port bellard/quickjs dtoa library commits

added new dtoa library to print and parse float64 numbers. It is necessary to fix corner cases (e.g. radix != 10) and to have correct behavior regardless of the libc implementation.

Port of:
bellard/quickjs@9936606
bellard/quickjs@dbbca3d

Includes alternative fix for bellard/quickjs@638ec8c from 0191aea

Remaining TODO items (would appreciate a look @saghul @bnoordhuis):

• Amalgamation fails due to duplicate symbols (not sure how you'd prefer to fix this?)
• Codegen update
• New test error 🤔 (see below - would appreciate a look at this one)

Result: 65/78606 errors, 3796 excluded, 5454 skipped, 2 new
test262/test/built-ins/TypedArrayConstructors/internals/Set/resized-out-of-bounds-to-in-bounds-index.js:18: unexpected error: Test262Error: Expected SameValue(«0», «100») to be true
test262/test/built-ins/TypedArrayConstructors/internals/Set/resized-out-of-bounds-to-in-bounds-index.js:18: strict mode: unexpected error: Test262Error: Expected SameValue(«0», «100») to be true

[bnoordhuis]

I have a fix for the first item in bnoordhuis/quickjs@2c073d7 that you can cherry-pick.

[saghul]

Can you run make gen? Looks like we're one bug away!