Convert fastboot to Soong

Also fix adb's version number to match.

See build/soong/README.md for more information.

Test: cd system/core/fastboot; mma
Test: fastboot --version
Test: adb --version
Test: out/host/linux-x86/nativetest/fastboot_test/fastboot_test
Test: out/host/linux-x86/nativetest64/fastboot_test/fastboot_test
Change-Id: I65ea39af9183c602e84f3bc0e4a0d066a30fc464