[clang] [clang][Driver] Include stdc-predef.h by default on musl (PR #202919)

[Jonathan Thackray via cfe-commits]

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@@ -0,0 +1,77 @@
+// Test that clang preincludes stdc-predef.h for musl Linux targets and
+// glibc Linux sysroots that provide the header.
+
+// Musl-based systems need this additional include.
+// RUN: %clang %s -### -c --target=x86_64-unknown-linux-musl \
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jthackray wrote:

Sure, increased line wrapping width, so only 2 `RUN` lines.

https://github.com/llvm/llvm-project/pull/202919