Use built-ins for addition and subtraction on Windows

[cmb69]

For Clang, we just need to define the respective macros, since these built-ins are available in all supported Clang versions (>= 4.0.0, currently)[1].

For MSVC (and possibly other compilers) we use the respective APIs of intsafe.h[2] which are available as of Windows 7/Server 2008 R2.

This avoids the UB due to signed integer overflow that may happen with our fallback implementations.

[1] https://releases.llvm.org/4.0.0/tools/clang/docs/LanguageExtensions.html
[2] https://learn.microsoft.com/en-us/windows/win32/api/intsafe/

[cmb69]

Need to check the test failures.

[cmb69]

I'll follow up with a similar improvement for ZEND_SIGNED_MULTIPLY_LONG() as soon as possible.

[dstogov]

For MSVC (and possibly other compilers) we use the respective APIs of intsafe.h[2] which are available as of Windows 7/Server 2008 R2.

If this is not a problem, I don't see other problems.

This avoids the UB due to signed integer overflow that may happen with our fallback implementations.

@nielsdos could you please take a look. This is probably may be fixed similar to your fix for the IR.

[cmb69]

If this is not a problem, […]

No problem. We require Windows 7/2008 RC2 as of PHP 7.2.0 already (and Windows 8/Server 2012 as of PHP 8.3.0).

@nielsdos could you please take a look. This is probably may be fixed similar to your fix for the IR.

Background: I've noticed the UB when running the Zend/test suite with Clang UBSan on Windows. At first I was very surprised that this hasn't come up already, but when looking at the code, I saw that there is already special casing for the most important compilers/systems (using either inline ASM or _builtin*()). So it might not be that important to fix the fallbacks.