__builtin_expect function isn't available in gcc below version 3

Dear Lua team

When compiling Lua 5.4.7 for Haiku targeting x86 32 bit using gcc 2 I encounter that '__builtin_expect' function isn't available. Btw, this specific x86 32 bit target of Haiku uses gcc version 2. This issue is also affecting Lua 5.4.8 and Lua 5.5.0.

I checked out the gcc 2.95 manual at https://gcc.gnu.org/onlinedocs/gcc-2.95.3/gcc_4.html and the gcc 3.0 manual at https://gcc.gnu.org/onlinedocs/gcc-3.0/gcc_5.html. I recognize that `__builtin_expect` is in the gcc 3.0 manual but not in the gcc 2.95 manual. From there I conclude that `__builtin_expect` is only available since gcc version 3.

Based on this conclusion, one of the Haiku developers Begasus and I created a patch. In the patchset of the Lua 5.4.7 compilation for Haiku at https://github.com/haikuports/haikuports/blob/master/dev-lang/lua/patches/lua-5.4.7.patchset
the patch is as follows.
```
diff --git a/src/luaconf.h b/src/luaconf.h
index 024aa7f..9e24be9 100644
--- a/src/luaconf.h
+++ b/src/luaconf.h
@@ -701,7 +701,7 @@
*/
#if !defined(luai_likely)

-#if defined(__GNUC__) && !defined(LUA_NOBUILTIN)
+#if defined(__GNUC__) && ((__GNUC__) >= 3) && !defined(LUA_NOBUILTIN)
#define luai_likely(x) (__builtin_expect(((x) != 0), 1))
#define luai_unlikely(x) (__builtin_expect(((x) != 0), 0))
#else
--
2.45.2
```

In this patch `((__GNUC__) >= 3)` is added to `defined(__GNUC__)` because only gcc 3 and above have support for `__builtin_expect`.

Sincerely,

Richard Beckmann
Sent with Proton Mail secure email.

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