Enable MemorySanitizer in CI tests

[intgr]

No description provided.

[intgr]

• Need to investigate MemorySanitizer output:

Uninitialized bytes in __interceptor_memchr at offset 0 inside [0x701000000000, 4)
==50==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x56223dbdf77e  (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0x9c77e)
    #1 0x56223dbe7cf1  (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0xa4cf1)
    #2 0x56223dbd04eb  (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0x8d4eb)
    #3 0x56223dbb5cc1  (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0x72cc1)
    #4 0x7f8b3ca1409a  (/lib/x86_64-linux-gnu/libc.so.6+0x2409a)
    #5 0x56223db4f1d9  (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0xc1d9)

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/root/build/target/debug/build/libc-e05582269760f0a4/build-script-build+0x9c77e) 

[intgr]

Issue very likely related to rust-lang/rust#39610

The good news is that the stack trace actually comes from libc's build-script-build script, not caused by posix-acl, and probably false positive. :)

[intgr]

Memory Sanitizer is extra tricky and also requires you to rebuild ALL linked code with it, including the standard library. See https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/sanitizer.html for details

I'd say this is not worth it, rebuilding the whole standard library would make the CI take unreasonably long. Closing for now.