ksymaddr-remote: allow providing nm name/path

[xairy]

When debugging the arm64 kernel from an x86 machine, using the x86 native nm does not work: aarch64-linux-gnu-nm needs to be used instead. It would be great if there was a way to configure the nm binary name/path.

Same likely applies to objcopy, objdump, readelf, c++filt (and gcc?).

[bata24]

Fixed.
See aaa5779.