[kernel] Make sure all vma types have (virtual) dtors

src/kernel/objects/vm_area.cpp

@@ -66,9 +66,7 @@ vm_area_fixed::vm_area_fixed(uintptr_t start, size_t size, vm_flags flags) :
 {
 }
 
-vm_area_fixed::~vm_area_fixed()
+vm_area_fixed::~vm_area_fixed() {}
-{
-}
 
 size_t vm_area_fixed::resize(size_t size)
 {
@@ -91,9 +89,7 @@ vm_area_untracked::vm_area_untracked(size_t size, vm_flags flags) :
 {
 }
 
-vm_area_untracked::~vm_area_untracked()
+vm_area_untracked::~vm_area_untracked() {}
-{
-}
 
 bool
 vm_area_untracked::get_page(uintptr_t offset, uintptr_t &phys)
@@ -119,6 +115,8 @@ vm_area_open::vm_area_open(size_t size, vm_flags flags) :
 {
 }
 
+vm_area_open::~vm_area_open() {}
+
 bool
 vm_area_open::get_page(uintptr_t offset, uintptr_t &phys)
 {
@@ -134,6 +132,8 @@ vm_area_guarded::vm_area_guarded(uintptr_t start, size_t buf_pages, size_t size,
 {
 }
 
+vm_area_guarded::~vm_area_guarded() {}
+
 uintptr_t
 vm_area_guarded::get_section()
 {

src/kernel/objects/vm_area.h

@@ -114,6 +114,7 @@ public:
 	/// \arg size  Initial virtual size of the memory area
 	/// \arg flags Flags for this memory area
 	vm_area_open(size_t size, vm_flags flags);
+	virtual ~vm_area_open();
 
 	virtual bool get_page(uintptr_t offset, uintptr_t &phys) override;
 
@@ -155,6 +156,8 @@ public:
 		size_t size,
 		vm_flags flags);
 
+	virtual ~vm_area_guarded();
+
 	/// Get an available section in this area
 	uintptr_t get_section();