Avoid using fork() when probing system libstdc++
#60254
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Rather than relying on the linker to do all of the heavy lifting, this changes our probing technique to directly parse the `ld.so.cache` and `libstdc++.so.6` files. As long as we can expect `ld.so.cache` to be available in `/etc` on all systems, this seems to be a reliable way to locate system libraries on Linux systems. That allows us to avoid `fork()`. For a small application that has just started up `fork()` is no big deal, but it's quite heavy-handed for Julia- as-a-library scenarios where resident memory may already be large. Many soft-embedded targets also do not support fork() well, so it is good for our compatibility to adjust this.
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Somewhat of a companion to #60248.
For a small application that has just started up
fork()is not a huge concern, but it's quite heavy-handed for Julia- as-a-library scenarios where resident memory may already be large. Many soft-embedded targets also do not support fork() well, so it is good for our compatibility to adjust this.Rather than relying on the linker to do all of the heavy lifting, this changes our
libstdcxxprobe sequence to directly parse theld.so.cacheandlibstdc++.so.6files. As long as we can expect/etc/ld.so.cacheto be the same path on all Linux systems, this seems to be a reliable way to locate system libraries.