-Z profile broken since the upgrade to LLVM 11

[glandium]

The same errors as #50203 (cannot merge previous GCDA file: corrupt arc tag) are happening again, starting with nightly-2020-08-24 (5180f3d), which is the first nightly after #73526.

I'm using the flags -Zprofile -Ccodegen-units=1 -Cinline-threshold=0, and setting CARGO_INCREMENTAL=0 in the environment.

[glandium]

This looks like a LLVM issue purely. If I upgrade the C compiler to LLVM 11 too, then it works (this was on a crate with ffi code). I guess this is not something rust can do anything about.

[wllenyj]

The same problem reappeared in 1.60.0-nightly (09cb29c 2022-02-15)

    ubuntu: info: default toolchain set to 'nightly-x86_64-unknown-linux-gnu'
    ubuntu:   nightly-x86_64-unknown-linux-gnu installed - rustc 1.60.0-nightly (09cb29c64 2022-02-15)
    ubuntu: 
    ubuntu: 
    ubuntu: Rust is installed now. Great!

...

failures:

---- x86_64::mpspec::bindgen_test_layout_mpc_cpu stdout ----
---- x86_64::mpspec::bindgen_test_layout_mpc_cpu stderr ----
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x00000000)
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x00000001)
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x00000001)
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x75747375)
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x3638782d)
profiling: /vagrant/target/debug/deps/db_boot-f38d7d4bfa105ed8.gcda: cannot merge previous GCDA file: corrupt arc tag (0x696c2f75)

See https://github.com/wllenyj/dragonball-sandbox/runs/5212083346 for details.