[libc-commits] [libc] [libc] Update include directory for libcMPCommon target when LLVM_LIBC_MPFR_INSTALL_PATH is set. (PR #124765)

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lntue wrote:

> I thought #124702 was supposed to fix this build bot? I'm all for remove `-ffreestanding`, but are BOTH necessary to fix this build bot?

That one fixes other build bots that have libmpfr and libgmp installed in the system directories that they can find.  RISCV32 bot installed mpfr at different location, and use `LLVM_LIBC_MPFR_INSTALL_PATH` to point to that location, so this PR just adds that to the search path of the new target `libcMPCommon` similar to `libcMPFRWrapper` target.

https://github.com/llvm/llvm-project/pull/124765