[libc] [llvm] [libc] Improve qsort (PR #120450)

[Lukas Bergdoll via llvm-commits]

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@@ -15,9 +15,13 @@
 #define LIBC_QSORT_QUICK_SORT 1
 #define LIBC_QSORT_HEAP_SORT 2
 
+#ifdef LIBC_OPTIMIZE_FOR_SIZE
+#define LIBC_QSORT_IMPL LIBC_QSORT_HEAP_SORT
+#else
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Voultapher wrote:

I need more information here, my idea was to keep the existing `LIBC_CONF_QSORT_IMPL` flag for compatibility reasons and add a new one that could be re-used across different areas of the library. It's not immediately clear to me how to do that with `config.json` and what the implications would be, and even then it would have to be used here in this way also, no? 

https://github.com/llvm/llvm-project/pull/120450