resolves #2441

[stuartcarnie]

Convert ext-iconv to HNI

[sgolemon]

Made some minor edits on the way in.

• Killed ext_iconv.h - Nobody needs this file, and with static linkage they wouldn't be able to use it anyway
• Made string constants use global scope static strings - Don't want these destructing (not that they will currently, but things may change)
• Various lint fixed (trailing whitespace, 80col limit, etc...)

[JoelMarcey]

Internal Diff Number: D1279705

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[JoelMarcey]

@stuartcarnie Hi. We are close to landing this (we are probably going to land as-is, actually). But, we ran into some weird compilation issues in OSS around INT32_MAX not being in scope. We are still not sure why we have these issues, but it did raise a question.

Why do you have this line in iconv_substr of ext_iconv.cpp

length = length <= INT32_MAX ? length : INT32_MAX;

length is being declared in ext_iconv.php as PHP_INT_MAX which is 64-bit.

Why the downcast to INT32_MAX?

cc:/ @ptarjan

[stuartcarnie]

The downcast is because the implementation of _php_iconv_substr requires an int32_t, however upon reviewing the code (on my phone), there is no reason not to change the _php_iconv_* functions to use int64_t

Would you like me to do that - I know Sara has made some tweaks already, so it may not be practical.

[stuartcarnie]

It has been a while since I touched this, but I seem to recall I looked at leaving it as int64_t originally but ran into an issue that it wasn't working when JITting the code