[llvm] Enable exp10 libcall on linux (PR #68736)

[Matt Arsenault via llvm-commits]

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@@ -562,12 +562,9 @@ static void initialize(TargetLibraryInfoImpl &TLI, const Triple &T,
     // or we have a reasonable detection strategy, we cannot use exp10 reliably
     // on Linux.
     //
-    // Fall through to disable all of them.
-    [[fallthrough]];
-  default:
-    TLI.setUnavailable(LibFunc_exp10);
-    TLI.setUnavailable(LibFunc_exp10f);
-    TLI.setUnavailable(LibFunc_exp10l);
+    TLI.setAvailableWithName(LibFunc_exp10, "__exp10");
+    TLI.setAvailableWithName(LibFunc_exp10f, "__exp10f");
----------------
arsenm wrote:

I'm not talking about the exp10l. I'm talking about "exp10, exp10f, exp10l is available on Linux (GLIBC) but are extremely
    // buggy prior to glibc version 2.18. Until this version is widely deployed
     // or we have a reasonable detection strategy, we cannot use exp10 reliably
     // on Linux."

https://github.com/llvm/llvm-project/pull/68736