rebase: update vendored go-ceph to v0.6

Closes: #1547
Signed-off-by: Niels de Vos <ndevos@redhat.com>

vendor/github.com/ceph/go-ceph/internal/cutil/cutil.go

@@ -0,0 +1,14 @@
+package cutil
+
+import "unsafe"
+
+// VoidPtr casts a uintptr value to an unsafe.Pointer value in order to use it
+// directly as a void* argument in a C function call.
+// CAUTION: NEVER store the result in a variable, or the Go GC could panic.
+func VoidPtr(i uintptr) unsafe.Pointer {
+	var nullPtr unsafe.Pointer
+	// It's not possible to cast uintptr directly to unsafe.Pointer. Therefore we
+	// cast a null pointer to uintptr and apply pointer arithmetic on it, which
+	// allows us to cast it back to unsafe.Pointer.
+	return unsafe.Pointer(uintptr(nullPtr) + i)
+}