Kernel: Simplify VMObject::is_anonymous().

This doesn't need a separate flag. A VMObject is always anonymous if it has
no backing inode.

Kernel/VM/VMObject.cpp

@@ -33,7 +33,6 @@ Retained<VMObject> VMObject::clone()
 
 VMObject::VMObject(VMObject& other)
     : m_name(other.m_name)
-    , m_anonymous(other.m_anonymous)
     , m_inode_offset(other.m_inode_offset)
     , m_size(other.m_size)
     , m_inode(other.m_inode)
@@ -43,16 +42,14 @@ VMObject::VMObject(VMObject& other)
 }
 
 VMObject::VMObject(size_t size)
-    : m_anonymous(true)
-    , m_size(size)
+    : m_size(size)
 {
     MM.register_vmo(*this);
     m_physical_pages.resize(page_count());
 }
 
 VMObject::VMObject(PhysicalAddress paddr, size_t size)
-    : m_anonymous(true)
-    , m_size(size)
+    : m_size(size)
 {
     MM.register_vmo(*this);
     for (size_t i = 0; i < size; i += PAGE_SIZE) {

Kernel/VM/VMObject.h

@@ -22,7 +22,7 @@ public:
     Retained<VMObject> clone();
 
     ~VMObject();
-    bool is_anonymous() const { return m_anonymous; }
+    bool is_anonymous() const { return !m_inode; }
 
     Inode* inode() { return m_inode.ptr(); }
     const Inode* inode() const { return m_inode.ptr(); }
@@ -49,10 +49,9 @@ private:
     template<typename Callback> void for_each_region(Callback);
 
     String m_name;
-    bool m_anonymous { false };
+    bool m_allow_cpu_caching { true };
     off_t m_inode_offset { 0 };
     size_t m_size { 0 };
-    bool m_allow_cpu_caching { true };
     RetainPtr<Inode> m_inode;
     Vector<RetainPtr<PhysicalPage>> m_physical_pages;
     Lock m_paging_lock { "VMObject" };