Update kernels
- Add 5.0 kernels
- Add kernel version to name
- Set TCVERSION in kernel Makefiles
Correct kernel related dirs
Update toolchains
- Add version to toolchain names
- Add DSM5.0 Toolchains
- Add x64 toolchain
- Set TC_ARCH and TC_FIRMWARE variables
Export TC_FIRMWARE and TC_ARCH to tcvars.mk
Add DEFAULT_TC to Makefile
Add multiple-TC-support to spk.mk and cross-cc.mk
- Use REQUIRED_DSM to set minimum toolchain version in Makefile
- Arch in INFO is set via  TC_ARCH. Override with `override SPK_ARCH= ...`
- Firmware in INFO is set via TC_FIRMWARE. Override with `FIRMWARE = ...`
- cross-cc: If REQ_KERNEL is set, x64 cannot be used
New rules
- `all-archs-%` builds all archs where specified toolchain is available
- `latest-arch-% builds for specified arch with latest available toolchain
- `all-archs-dsms` builds all archs based on latest major toolchain
Merge pull request #1276 from Dr-Bean/toolchains

Multiple TCs