perf annotate-data: Handle global variable access with const register

perf annotate-data: Handle global variable access with const register

When a register holds a constant value (TSR_KIND_CONST) and is used with
a negative offset, treat it as a potential global variable access
instead of falling through to CFA (frame) handling.

This fixes cases like array indexing with computed offsets:

    movzbl -0x7d72725a(%rax), %eax   # array[%rax]

Where %rax contains a computed index and the negative offset points to a
global array. Previously this fell through to the CFA path which doesn't
handle global variables, resulting in "no type information".

The fix redirects such accesses to check_kernel which calls
get_global_var_type() to resolve the type from the global variable
cache. This is only done for kernel DSOs since the pattern relies on
kernel-specific global variable resolution. We could also treat
registers with integer types to the global variable path, but this
requires more changes.

Signed-off-by: Zecheng Li <zli94@ncsu.edu>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>