Add basic exFAT support.

Several partners have been requesting exFAT support.  Android doesn't
natively support exFAT, but we're at least willing to try mounting an
exFAT filesystem if we detect the Linux kernel supports it, and if
helper binaries are present.

This CL is simple scaffolding, and it provides no actual
implementation of exFAT.

Test: builds, boots
Bug: 67822822
Change-Id: Id4f8ec3967b32de6e1c0e3c4b47fe6e43a6291ab
diff --git a/model/Disk.cpp b/model/Disk.cpp
index 9b772e4..becf8b7 100644
--- a/model/Disk.cpp
+++ b/model/Disk.cpp
@@ -364,12 +364,13 @@
                 }
 
                 switch (type) {
-                case 0x06: // FAT16
-                case 0x0b: // W95 FAT32 (LBA)
-                case 0x0c: // W95 FAT32 (LBA)
-                case 0x0e: // W95 FAT16 (LBA)
-                    createPublicVolume(partDevice);
-                    break;
+                    case 0x06:  // FAT16
+                    case 0x07:  // HPFS/NTFS/exFAT
+                    case 0x0b:  // W95 FAT32 (LBA)
+                    case 0x0c:  // W95 FAT32 (LBA)
+                    case 0x0e:  // W95 FAT16 (LBA)
+                        createPublicVolume(partDevice);
+                        break;
                 }
             } else if (table == Table::kGpt) {
                 if (++it == split.end()) continue;