drgn could use libkdumpfile for more crash dumps

[jwadams]

drgn has issues with regular kernel core files; things like module data etc aren't readable. By default, drgn only used libkdumpfile for "KDUMP" files. I was able to work around this by:

--- a/libdrgn/program.c
+++ b/libdrgn/program.c
@@ -195,7 +195,7 @@ drgn_program_set_core_dump(struct drgn_program *prog, const char *path)
        err = has_kdump_signature(path, prog->core_fd, &is_kdump);
        if (err)
                goto out_fd;
-       if (is_kdump) {
+       if (is_kdump || 1) {
                err = drgn_program_set_kdump(prog);
                if (err)
                        goto out_fd;

which just forces the use of kdumpfile, but that prevents user-space core file handling and is a bit of a hack. Some way to use kdumpfile for kernel cores would be nice, since it handles all of the complicated address space stuff.