Add exfat utilities for mkfs and fsck

Bug: 171854784
Test: Builds, Large sdcards formated as exfat if kernel supports it
Change-Id: Ie56b17f55f5027fdf714002b4c307603809fb707

Author: drosen-google

shell_and_utilities/Android.bp

@@ -18,9 +18,11 @@ phony {
         "awk",
         "bc",
         "bzip2",
+        "fsck.exfat",
         "ldd",
         "logwrapper",
         "mini-keyctl",
+        "mkfs.exfat",
         "mkshrc",
         "newfs_msdos",
         "reboot",