[kernel] Spit out vm_area types

The vm_space allow() functionality was a bit janky; using VMAs for all
regions would be a lot cleaner. To that end, this change:

- Adds a "static array" ctor to kutil::vector for setting the kernel
  address space's VMA list. This way a kernel heap VMA can be created
  without the heap already existing.
- Splits vm_area into different subclasses depending on desired behavior
- Splits out the concept of vm_mapper which maps vm_areas to vm_spaces,
  so that some kinds of VMA can be inherently single-space
- Implements VMA resizing so that userspace can grow allocations.
- Obsolete page_table_indices is removed

Also, the following bugs were fixed:

- kutil::map iterators on empty maps no longer break
- memory::page_count was doing page-align, not page-count

See: Github bug #242
See: [frobozz blog post](https://jsix.dev/posts/frobozz/)

Tags:

src/libraries/libc/arch/x86_64/syscalls.s

@@ -4,7 +4,11 @@
 		push rbp
 		mov rbp, rsp
 
-		; address of args should already be in rdi, etc
+		; args should already be in rdi, etc, but rcx will
+		; get stomped, so shift args out one spot from rcx
+		mov r9, r8
+		mov r8, rcx
+
 		mov rax, %2
 		syscall
 		; result is now already in rax, so just return
@@ -17,5 +21,7 @@
 %define SYSCALL(n, name, a) SYSCALL name, n
 %define SYSCALL(n, name, a, b) SYSCALL name, n
 %define SYSCALL(n, name, a, b, c) SYSCALL name, n
+%define SYSCALL(n, name, a, b, c, d) SYSCALL name, n
+%define SYSCALL(n, name, a, b, c, d, e) SYSCALL name, n
 
 %include "syscalls.inc"