Binary descriptions:

libc6-armel-armhf-cross: Dummy package to get libc6:armel installed
libc6-armhf-cross: Embedded GNU C Library: Shared libraries (for cross-compiling)
libc6-dbg-armhf-cross: Embedded GNU C Library: detached debugging symbols (for cross-compiling)
libc6-dev-armel-armhf-cross: Dummy package to get libc6-dev:armel installed
libc6-dev-armhf-cross: Embedded GNU C Library: Development Libraries and Header Files (for cross-compiling)
linux-libc-dev-armhf-cross: Linux Kernel Headers for development (for cross-compiling)