Enable GDB for binutils 2.40 with native AmigaOS debugging fixes

[derfsss]

Summary

• Enable GDB in both cross and native binutils 2.40 builds (remove --disable-gdb, add --with-python=no)
• Add gild patch 0002-Fix-GDB-native-debugging-on-AmigaOS-4.patch with fixes for native GDB on AmigaOS 4
• Add GDB test targets to tests/makefile

GDB Fixes (patch 0002)

Register handling:

• Fix fetch_registers() GPR loop indexing (used regno instead of loop variable)
• Fix FPR index offset (subtract base register number)
• Fix loop bounds: 32 registers not 31
• Gate AltiVec register access on ECF_VECTOR context flag
• Implement store_registers() using IDebug->WriteTaskContext()

Trap/signal handling:

• Replace raw PPC vector numbers with SDK TRAPNUM_* values from exec/interrupts.h
• Add handling for TRAP_TRAP (breakpoints), TRAP_DATA_BREAKPOINT (DABR), TRAP_TRACE (single-step)
• Preserve actual signal type in wait() instead of collapsing to GDB_SIGNAL_0

Process control:

• Implement attach() for connecting to running processes
• Fix kill() to use Signal(SIGBREAKF_CTRL_C) + RestartTask instead of DeleteTask on Process objects
• Add message pool safety with NULL checks in debug callback

BFD file path fix:

• Skip canonicalize_file_name() on AmigaOS in gdb_realpath() — AmigaOS realpath() resolves assigns (e.g. T: becomes RAM Disk:T/) producing paths that fail when BFD's file cache tries to reopen them

Charset fix:

• Force UTF-8 host charset on AmigaOS — clib4's nl_langinfo(CODESET) returns ISO-8859-1 but its iconv cannot reliably convert to UTF-32

Test plan

• Cross-GDB builds on Linux host
• Native GDB tested on AmigaOS 4.1 (Pegasos II via QEMU)
• info functions — DWARF symbols with source file and line numbers
• disassemble — correct PPC instruction dump
• break — breakpoints resolved to source locations
• ptype — struct, enum, union, function types
• x/ — memory examination (hex, instructions, strings)
• maintenance info sections — all sections including .debug_*
• No locale/charset warnings
• Patches apply cleanly to fresh gild checkout binutils 2.40

🤖 Generated with Claude Code

[migthymax]

Based on your work i created a PR against the binutils-gdb project containing your changes. There I will comment about it.