v1.21.1
[crypto] Add DER image format
[efi] Split device path functions out to efi_path.c
[elf] Reject ELFBoot images requiring virtual addressing
[build] Allow assembler section type character to vary by architecture
[crypto] Expose pem_asn1() for use with non-image data
[png] Fix potential integer overflow
[legal] Relicense files under GPL2_OR_LATER_OR_UBDL