Fixes VMR creating off-by-one

If a VMR would just barely fit before the first VMR, we would fail to
use that slot.

Practically, this only happens if you decide to do a MAP_FIXED at a low
address, which will unmap a chunk of ld.so - not recommended!

kern/arch/x86/ros/mmu64.h

diff --git a/kern/arch/x86/ros/mmu64.h b/kern/arch/x86/ros/mmu64.h
index be2058e..9e692be 100644
--- a/kern/arch/x86/ros/mmu64.h
+++ b/kern/arch/x86/ros/mmu64.h
@@ -118,6 +118,13 @@
  *                     |     Program Data & Heap      |
  *                     |                              |
  *                     +------------------------------+ 0x0000000000400000
+ *                     .                              .
+ *                     .                              .
+ *                     |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
+ *                     |                              |
+ *                     |       ld.so (Dynamic)        |
+ *                     |                              |
+ * MMAP_LOWEST_VA      +------------------------------+ 0x0000000000100000
  *                     |                              |
  *                     |       Empty Memory (*)       |
  *                     |                              |

kern/src/mm.c

diff --git a/kern/src/mm.c b/kern/src/mm.c
index 2b10536..bf93513 100644
--- a/kern/src/mm.c
+++ b/kern/src/mm.c
@@ -58,7 +58,7 @@
 	vm_i = TAILQ_FIRST(&p->vm_regions);
 	/* This works for now, but if all we have is BRK_END ones, we'll start
 	 * growing backwards (TODO) */
-	if (!vm_i || (va + len < vm_i->vm_base)) {
+	if (!vm_i || (va + len <= vm_i->vm_base)) {
 		vmr = kmem_cache_alloc(vmr_kcache, 0);
 		if (!vmr)
 			panic("EOM!");