Add support for x86 VirtualBox Emulation

To make a VirtualBox install image,
  make installer_img
diff --git a/target/board/generic_x86/disk_layout.conf b/target/board/generic_x86/disk_layout.conf
new file mode 100644
index 0000000..7b073ee
--- /dev/null
+++ b/target/board/generic_x86/disk_layout.conf
@@ -0,0 +1,54 @@
+device {
+    path /dev/block/sda
+
+    scheme mbr
+
+    # bytes in a disk sector (== 1 LBA), must be a power of 2!
+    sector_size 512
+
+    # What LBA should the partitions start at?
+    start_lba 2048
+
+    # Autodetect disk size if == 0
+    num_lba 0
+
+    partitions {
+        sysloader {
+            active y
+            type linux
+            len 7M
+        }
+
+        recovery {
+            active y
+            type linux
+            len 16M
+        }
+
+        boot {
+            active y
+            type linux
+            len 8M
+        }
+
+        cache {
+            type linux
+            len 512M
+        }
+
+        system {
+            type linux
+            len 512M
+        }
+
+        third_party {
+            type linux
+            len 512M
+        }
+
+        data {
+            type linux
+            len -1
+        }
+    }
+}