btf: require pahole 1.21+ for DEBUG_INFO_BTF with default DWARF version

As described in commit 42d9b37 ("lib/Kconfig.debug: Allow BTF +
DWARF5 with pahole 1.21+"), the combination of CONFIG_DEBUG_INFO_BTF
and CONFIG_DEBUG_INFO_DWARF5 requires pahole 1.21+.

GCC 11+ and Clang 14+ default to DWARF 5 when the -g flag is passed.
For the same reason, the combination of CONFIG_DEBUG_INFO_BTF and
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT is also likely to require
pahole 1.21+ these days. (At least, it is uncertain whether the actual
requirement is pahole 1.16+ or 1.21+.)

Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Alan Maguire <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: masahir0y

lib/Kconfig.debug

@@ -380,7 +380,7 @@ config DEBUG_INFO_BTF
 	depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST
 	depends on BPF_SYSCALL
 	depends on PAHOLE_VERSION >= 116
-	depends on !DEBUG_INFO_DWARF5 || PAHOLE_VERSION >= 121
+	depends on DEBUG_INFO_DWARF4 || PAHOLE_VERSION >= 121
 	# pahole uses elfutils, which does not have support for Hexagon relocations
 	depends on !HEXAGON
 	help