kbuild: dwarf: use AS_VERSION instead of test_dwarf5_support.sh

The test code in scripts/test_dwarf5_support.sh is somewhat difficult
to understand, but after all, we want to check binutils >= 2.35.2

From the former discussion, the requirement for generating DWARF v5 from
C code is as follows:

 - gcc + gnu as          -> requires gcc 5.0+ (but 7.0+ for full support)
 - clang + gnu as        -> requires binutils 2.35.2+
 - clang + integrated as -> OK

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

lib/Kconfig.debug

@@ -284,8 +284,7 @@ config DEBUG_INFO_DWARF4
 
 config DEBUG_INFO_DWARF5
 	bool "Generate DWARF Version 5 debuginfo"
-	depends on GCC_VERSION >= 50000 || CC_IS_CLANG
-	depends on CC_IS_GCC || $(success,$(srctree)/scripts/test_dwarf5_support.sh $(CC) $(CLANG_FLAGS))
+	depends on GCC_VERSION >= 50000 || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502)))
 	depends on !DEBUG_INFO_BTF
 	help
 	  Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc