unwinding/dwarf: Support DWARF CFA opcode: 0x26

[brancz]

Found in the wild by a Polar Signals Cloud customer:

panic: Encountered an unexpected DWARF CFA opcode: 0x26
goroutine 240 [running]:
github.com/parca-dev/parca-agent/internal/dwarf/frame.lookupFunc(0x50?, 0x1bdbac4?)
	github.com/parca-dev/parca-agent/internal/dwarf/frame/table.go:404 +0x360
github.com/parca-dev/parca-agent/internal/dwarf/frame.executeDWARFInstruction(0x4000c34a50)
	github.com/parca-dev/parca-agent/internal/dwarf/frame/table.go:309 +0x84
github.com/parca-dev/parca-agent/internal/dwarf/frame.(*InstructionContextIterator).Next(0x40024fb730)
	github.com/parca-dev/parca-agent/internal/dwarf/frame/table.go:90 +0x5c
github.com/parca-dev/parca-agent/pkg/stack/unwind.BuildCompactUnwindTable({0x4000bf6000, 0xcdd, 0x1000?}, 0xadd0?)
	github.com/parca-dev/parca-agent/pkg/stack/unwind/compact_unwind_table.go:157 +0x2c8
github.com/parca-dev/parca-agent/pkg/stack/unwind.GenerateCompactUnwindTable({0x40023f69c0?, 0x4b0?})
	github.com/parca-dev/parca-agent/pkg/stack/unwind/compact_unwind_table.go:283 +0x60
github.com/parca-dev/parca-agent/pkg/profiler/cpu/bpf/maps.(*Maps).setUnwindTableForMapping(0x40005ee600, 0x37?, 0x0?, 0x4000924840)
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/bpf/maps/maps.go:1557 +0xab8
github.com/parca-dev/parca-agent/pkg/profiler/cpu/bpf/maps.(*Maps).AddUnwindTableForProcess(0x40005ee600, 0xd1c, {0x0, 0x0, 0x0}, 0x1, 0x0)
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/bpf/maps/maps.go:1211 +0x604
github.com/parca-dev/parca-agent/pkg/profiler/cpu.(*CPU).addUnwindTableForProcess(0x400232da40, {0x29dbae8, 0x4000afd9e0}, 0x0?)
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/cpu.go:573 +0x478
github.com/parca-dev/parca-agent/pkg/profiler/cpu.(*CPU).onDemandUnwindInfoBatcher.func1({0x4000ac8180, 0x5, 0x29dba78?})
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/cpu.go:536 +0x5c
github.com/parca-dev/parca-agent/pkg/profiler/cpu.processEventBatcher({0x29dbae8, 0x4000afd9e0}, 0x400013e840, 0x0?, 0x40022cbf78)
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/cpu.go:619 +0x180
github.com/parca-dev/parca-agent/pkg/profiler/cpu.(*CPU).onDemandUnwindInfoBatcher(0x0?, {0x29dbae8?, 0x4000afd9e0?}, 0x4000140cc0?)
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/cpu.go:534 +0x5c
created by github.com/parca-dev/parca-agent/pkg/profiler/cpu.(*CPU).Run in goroutine 229
	github.com/parca-dev/parca-agent/pkg/profiler/cpu/cpu.go:857 +0x1094