Normalize hex addresses in zjit_diff stat keys

[rwstauner]

Strip memory addresses (0x...) from stat keys so entries that differ only by object address (e.g. "#Module:0x00007f1a#foo") are collapsed and their values summed for comparison.

$ jq . data/output_272.json | grep -E Module.+object_id
          "not_inlined_cfuncs_#<Module:0x000000012a3521c0>#object_id": 26,
          "not_annotated_cfuncs_#<Module:0x000000012a3521c0>#object_id": 26,
          "ccall_#<Module:0x000000012a3521c0>#object_id": 26,
          "not_inlined_cfuncs_#<Module:0x000000010ff26240>#object_id": 25,
          "not_annotated_cfuncs_#<Module:0x000000010ff26240>#object_id": 25,
          "ccall_#<Module:0x000000010ff26240>#object_id": 25,

$ misc/zjit_diff.rb data/output_272.json -a | grep -E Module.+object_id
    #<Module:0x…>#object_id                           26 →             25 ▼   -3.8%
    #<Module:0x…>#object_id                           26 →             25 ▼   -3.8%
    #<Module:0x…>#object_id                           26 →             25 ▼   -3.8%