Cleanup: rename all internal symbols

Global symbols that are only used internally by the library should
have a name that minimizes the risk of clashes with the application.
This is not an issue for dynamic link (where the linker map file takes
care of hiding these symbols), but it may happen in a static link.

Use a preprocessor macro to do the rename, so that the (ugly) real
names are not seen in the source files.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Cleanup: drop "kdump_" prefix from internal functions

This prefix was intended to prevent name collisions for library-internal
symbols. With the previous commit, it is no longer needed, and shorter
names save some typing...

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Cleanup: declare format ops and arch ops extern

This is in fact an omission that was hidden because of COMDEFs, but
each of these structure must have an actual definition. In other
words, COMDEF was not intended for these variables.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>