perf annotate: Fix source code annotate with objdump

perf annotate: Fix source code annotate with objdump

Recently it uses llvm and capstone to speed up annotation or disassembly
of instructions.  But they don't support source code view yet.  Until it
fixed, we can force to use objdump for source code annotation.

To prevent performance loss, it's disabled by default and turned it on
when user requests it in TUI by pressing 's' key.

Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250625230339.702610-1-namhyung@kernel.org
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>