addr2line: -C should not try to handle optional (ignored) argument

addr2line: -C should not try to handle optional (ignored) argument

The --demangle option takes an option (ignored) argument. Since -C
is the short option of --demangle it also takes that optional
argument. But that means that something like -Cfi is like -C got
fi as argument, while the user expects -Cfi to be like -C -f -i.

Separate the --demangle and -C options. --demangle still takes
an optional (ignored) argument, but -C doesn't take any arguments
so -Cfi acts the same as -fiC.

Also fix --target, -b, so that it is properly ignored (and not
accidentially enables demangling).

Signed-off-by: Mark Wielaard <mark@klomp.org>