github/test: Run tests with address sanitizer

We have lots of cgo interaction here so better to check things fully.

This also requires manually checking for leaks, so add support for this.

utils.go

@@ -0,0 +1,31 @@
+// Package pam provides a wrapper for the PAM application API.
+package pam
+
+/*
+#ifdef __SANITIZE_ADDRESS__
+#include <sanitizer/lsan_interface.h>
+#endif
+
+static inline void
+maybe_do_leak_check (void)
+{
+#ifdef __SANITIZE_ADDRESS__
+	__lsan_do_leak_check();
+#endif
+}
+*/
+import "C"
+
+import (
+	"os"
+	"runtime"
+	"time"
+)
+
+func maybeDoLeakCheck() {
+	runtime.GC()
+	time.Sleep(time.Millisecond * 20)
+	if os.Getenv("GO_PAM_SKIP_LEAK_CHECK") == "" {
+		C.maybe_do_leak_check()
+	}
+}