kbuild: split DEBUG_CFLAGS out to scripts/Makefile.debug

To slim down the top Makefile, split out the code block surrounded by
ifdef CONFIG_DEBUG_INFO ... endif.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesauniers@google.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>

Makefile

@@ -847,44 +847,6 @@ ifdef CONFIG_ZERO_CALL_USED_REGS
 KBUILD_CFLAGS	+= -fzero-call-used-regs=used-gpr
 endif
 
-DEBUG_CFLAGS	:=
-
-ifdef CONFIG_DEBUG_INFO
-
-ifdef CONFIG_DEBUG_INFO_SPLIT
-DEBUG_CFLAGS	+= -gsplit-dwarf
-else
-DEBUG_CFLAGS	+= -g
-endif
-
-ifndef CONFIG_AS_IS_LLVM
-KBUILD_AFLAGS	+= -Wa,-gdwarf-2
-endif
-
-ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
-dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
-dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5
-DEBUG_CFLAGS	+= -gdwarf-$(dwarf-version-y)
-endif
-
-ifdef CONFIG_DEBUG_INFO_REDUCED
-DEBUG_CFLAGS	+= -fno-var-tracking
-ifdef CONFIG_CC_IS_GCC
-DEBUG_CFLAGS	+= -femit-struct-debug-baseonly
-endif
-endif
-
-ifdef CONFIG_DEBUG_INFO_COMPRESSED
-DEBUG_CFLAGS	+= -gz=zlib
-KBUILD_AFLAGS	+= -gz=zlib
-KBUILD_LDFLAGS	+= --compress-debug-sections=zlib
-endif
-
-endif # CONFIG_DEBUG_INFO
-
-KBUILD_CFLAGS += $(DEBUG_CFLAGS)
-export DEBUG_CFLAGS
-
 ifdef CONFIG_FUNCTION_TRACER
 ifdef CONFIG_FTRACE_MCOUNT_USE_CC
   CC_FLAGS_FTRACE	+= -mrecord-mcount
@@ -1033,6 +995,7 @@ KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
 
 # include additional Makefiles when needed
 include-y			:= scripts/Makefile.extrawarn
+include-$(CONFIG_DEBUG_INFO)	+= scripts/Makefile.debug
 include-$(CONFIG_KASAN)		+= scripts/Makefile.kasan
 include-$(CONFIG_KCSAN)		+= scripts/Makefile.kcsan
 include-$(CONFIG_UBSAN)		+= scripts/Makefile.ubsan

scripts/Makefile.debug

+DEBUG_CFLAGS	:=
+
+ifdef CONFIG_DEBUG_INFO_SPLIT
+DEBUG_CFLAGS	+= -gsplit-dwarf
+else
+DEBUG_CFLAGS	+= -g
+endif
+
+ifndef CONFIG_AS_IS_LLVM
+KBUILD_AFLAGS	+= -Wa,-gdwarf-2
+endif
+
+ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
+dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
+dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5
+DEBUG_CFLAGS	+= -gdwarf-$(dwarf-version-y)
+endif
+
+ifdef CONFIG_DEBUG_INFO_REDUCED
+DEBUG_CFLAGS	+= -fno-var-tracking
+ifdef CONFIG_CC_IS_GCC
+DEBUG_CFLAGS	+= -femit-struct-debug-baseonly
+endif
+endif
+
+ifdef CONFIG_DEBUG_INFO_COMPRESSED
+DEBUG_CFLAGS	+= -gz=zlib
+KBUILD_AFLAGS	+= -gz=zlib
+KBUILD_LDFLAGS	+= --compress-debug-sections=zlib
+endif
+
+KBUILD_CFLAGS += $(DEBUG_CFLAGS)
+export DEBUG_CFLAGS