Use LazyLock for openssl probe (#607)

This switches the global static openssl probe to use LazyLock instead of
Once. `static mut` refs are now an error in Rust 2024, and this is I
believe the preferred method of doing something like this.

LazyLock was added in 1.80 (released 2024-07-25), so the minimum version
has to be bumped to that.

Author: ehuss

.github/workflows/main.yml

@@ -21,7 +21,7 @@ jobs:
             target: x86_64-unknown-linux-gnu
           - build: ubuntu-lts
             os: ubuntu-24.04
-            rust: 1.75
+            rust: '1.80'
             docker: linux64
             target: x86_64-unknown-linux-gnu
           - build: x86_64-beta

src/easy/handler.rs

@@ -676,22 +676,17 @@ impl<H: Handler> Easy2<H> {
 
     #[cfg(need_openssl_probe)]
     fn ssl_configure(&mut self) {
-        use std::sync::Once;
-
-        static mut PROBE: Option<::openssl_probe::ProbeResult> = None;
-        static INIT: Once = Once::new();
+        use std::sync::LazyLock;
 
         // Probe for certificate stores the first time an easy handle is created,
         // and re-use the results for subsequent handles.
-        INIT.call_once(|| unsafe {
-            PROBE = Some(::openssl_probe::probe());
-        });
-        let probe = unsafe { PROBE.as_ref().unwrap() };
+        static PROBE: LazyLock<openssl_probe::ProbeResult> =
+            LazyLock::new(|| openssl_probe::probe());
 
-        if let Some(ref path) = probe.cert_file {
+        if let Some(ref path) = PROBE.cert_file {
             let _ = self.cainfo(path);
         }
-        if let Some(ref path) = probe.cert_dir {
+        if let Some(ref path) = PROBE.cert_dir {
             let _ = self.capath(path);
         }
     }