nativeunwind: fix Go 1.26

[florianl]

As mentioned by @bobrik in #1032 (comment) I introduced a bug when handling Go 1.26 with #1032.

Due to the incorrect break statement, g.funcMapSize and g.funSize are not set correctly and therefore break stack unwinding.

How to test this change:

--- a/Makefile
+++ b/Makefile
@@ -72,7 +72,7 @@ ebpf: generate
        $(MAKE) $(EBPF_FLAGS) -C support/ebpf
 
 ebpf-profiler: generate ebpf
-       go build $(GO_FLAGS) -tags $(GO_TAGS)
+       GOTOOLCHAIN=go1.26rc2 go build $(GO_FLAGS) -tags $(GO_TAGS)
 

When handling Go 1.26 binaries, there is still a log entry, like level=ERROR msg="Failed to load /path/to/my/go/1.26/binary: unsupported Go version go1.26rc2 (need >= 1.13 and <= 1.25)". This log entry originates from the Go labels handling - which I didn't look into yet. My priority is/was being able to handle stack unwinding.

[fabled]

coredump test case would be nice