Panic due to overflow in `_cycles_per_sec()`

[Stypox]

I got this crash earlier, in the _cycles_per_sec() function, and I can sometimes reproduce it randomly and rarely. Apparently tsc2 < tsc1, which should be impossible...

If you also can't reproduce feel free to close this issue, I'm reporting it just in case it can help.

thread '<unnamed>' panicked at /home/USER/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/fastant-0.1.10/src/tsc_now.rs:170:34:
attempt to subtract with overflow
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

thread '<unnamed>' panicked at library/core/src/panicking.rs:218:5:
panic in a function that cannot unwind
stack backtrace:
   0:     0x560ec098623a - std::backtrace_rs::backtrace::libunwind::trace::h88deb10bd0145eb8
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x560ec098623a - std::backtrace_rs::backtrace::trace_unsynchronized::he1036f5481c14dff
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x560ec098623a - std::sys::backtrace::_print_fmt::hecc345b6e70c4b20
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/sys/backtrace.rs:66:9
   3:     0x560ec098623a - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::he089f96442833f67
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/sys/backtrace.rs:39:26
   4:     0x560ec09a5573 - core::fmt::rt::Argument::fmt::h1f77cded99c71a14
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/fmt/rt.rs:177:76
   5:     0x560ec09a5573 - core::fmt::write::h2f210ed4c94745cb
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/fmt/mod.rs:1440:21
   6:     0x560ec09837e3 - std::io::Write::write_fmt::h7de08171ab770fb2
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/io/mod.rs:1887:15
   7:     0x560ec0986082 - std::sys::backtrace::BacktraceLock::print::h810fbd31421329e6
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/sys/backtrace.rs:42:9
   8:     0x560ec0987220 - std::panicking::default_hook::{{closure}}::hbaad47ed9dc6356d
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/panicking.rs:295:22
   9:     0x560ec0987000 - std::panicking::default_hook::h24e207139139d40a
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/panicking.rs:322:9
  10:     0x560ec0987892 - std::panicking::rust_panic_with_hook::ha9131beeb2ddc506
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/panicking.rs:828:13
  11:     0x560ec09876f6 - std::panicking::begin_panic_handler::{{closure}}::h1bba0eaeb6da506f
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/panicking.rs:694:13
  12:     0x560ec0986739 - std::sys::backtrace::__rust_end_short_backtrace::h1d1ca3eade483f4c
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/sys/backtrace.rs:168:18
  13:     0x560ec09873bd - rust_begin_unwind
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/std/src/panicking.rs:692:5
  14:     0x560ec089796d - core::panicking::panic_nounwind_fmt::runtime::hdd2d1a56a8b6cee7
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/panicking.rs:117:22
  15:     0x560ec089796d - core::panicking::panic_nounwind_fmt::h0d5ff668f956fac4
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/intrinsics/mod.rs:3869:9
  16:     0x560ec0897a02 - core::panicking::panic_nounwind::h385b7d9bda51382d
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/panicking.rs:218:5
  17:     0x560ec0897b65 - core::panicking::panic_cannot_unwind::h757b6ea37bf9b60a
                               at /rustc/4d91de4e48198da2e33413efdcd9cd2cc0c46688/library/core/src/panicking.rs:307:5
  18:     0x560ec0898161 - fastant::tsc_now::___init___ctor::___init___ctor::h46fb9483f0334d4a
                               at /home/USER/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/fastant-0.1.10/src/tsc_now.rs:24:1
  19:     0x7f191a20b5c4 - __libc_start_main
  20:     0x560ec0898195 - _start
  21:                0x0 - <unknown>
thread caused non-unwinding panic. aborting.