[libcxx] [llvm] [libc++] Add support for picolibc and newlib in RUNTIMES_USE_LIBC (PR #147956)

[Volodymyr Turanskyy via llvm-commits]

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@@ -42,6 +42,10 @@
 // Hardening.
 #cmakedefine _LIBCPP_HARDENING_MODE_DEFAULT @_LIBCPP_HARDENING_MODE_DEFAULT@
 
+// C libraries
+#cmakedefine01 _LIBCXX_LIBC_PICOLIBC
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voltur01 wrote:

Thank you for the review and good point - I renamed the options.

https://github.com/llvm/llvm-project/pull/147956