Make TWRP compile for arm64

-Remove dosfstools for arm64 until we can make it compile
-Fix TW_USE_TOOLBOX flag to work again
-Fix symlinking and handling of sh when using mksh
-Fix legacy properties to find futex_wake function
-Fix libcrecovery to not use bsd_signal anymore
-Fix rules for building with regards to libcrecovery
-Update toolbox_recovery rules to compile tools in lollipop
-Fix a few compile errors specific to arm64

Testers report that TWRP does not boot on Nexus 9 and we fail to
get a shell for adb shell. At least it compiles without errors.

Change-Id: I286be8628defb60cc527b8a548c0bdfcb0ebb574