kbuild: use 4-space indentation when followed by conditionals

GNU Make manual [1] clearly forbids a tab at the beginning of the
conditional directive line:
 "Extra spaces are allowed and ignored at the beginning of the
  conditional directive line, but a tab is not allowed."

This will not work for the next release of GNU Make, hence commit
82175d1f ("kbuild: Replace tabs with spaces when followed by
conditionals") replaced the inappropriate tabs with 8 spaces.

However, the 8-space indentation cannot be visually distinguished.
Linus suggested 2-4 spaces for those nested if-statements. [2]

This commit redoes the replacement with 4 spaces.

[1]: https://www.gnu.org/software/make/manual/make.html#Conditional-Syntax
[2]: https://lore.kernel.org/all/CAHk-=whJKZNZWsa-VNDKafS_VfY4a5dAjG-r8BZgWk_a-xSepw@mail.gmail.com/Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Makefile

@@ -294,15 +294,15 @@ may-sync-config	:= 1
 single-build	:=
 
 ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
-        ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
+    ifeq ($(filter-out $(no-dot-config-targets), $(MAKECMDGOALS)),)
 		need-config :=
-        endif
+    endif
 endif
 
 ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
-        ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
+    ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
 		may-sync-config :=
-        endif
+    endif
 endif
 
 need-compiler := $(may-sync-config)
@@ -323,9 +323,9 @@ endif
 # We cannot build single targets and the others at the same time
 ifneq ($(filter $(single-targets), $(MAKECMDGOALS)),)
 	single-build := 1
-        ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),)
+    ifneq ($(filter-out $(single-targets), $(MAKECMDGOALS)),)
 		mixed-build := 1
-        endif
+    endif
 endif
 
 # For "make -j clean all", "make -j mrproper defconfig all", etc.

arch/m68k/Makefile

@@ -15,10 +15,10 @@
 KBUILD_DEFCONFIG := multi_defconfig
 
 ifdef cross_compiling
-        ifeq ($(CROSS_COMPILE),)
+    ifeq ($(CROSS_COMPILE),)
 		CROSS_COMPILE := $(call cc-cross-prefix, \
 			m68k-linux-gnu- m68k-linux- m68k-unknown-linux-gnu-)
-        endif
+    endif
 endif
 
 #

arch/parisc/Makefile

@@ -50,12 +50,12 @@ export CROSS32CC
 
 # Set default cross compiler for kernel build
 ifdef cross_compiling
-        ifeq ($(CROSS_COMPILE),)
+    ifeq ($(CROSS_COMPILE),)
 		CC_SUFFIXES = linux linux-gnu unknown-linux-gnu suse-linux
 		CROSS_COMPILE := $(call cc-cross-prefix, \
 			$(foreach a,$(CC_ARCHES), \
 			$(foreach s,$(CC_SUFFIXES),$(a)-$(s)-)))
-        endif
+    endif
 endif
 
 ifdef CONFIG_DYNAMIC_FTRACE

arch/x86/Makefile

@@ -112,13 +112,13 @@ ifeq ($(CONFIG_X86_32),y)
         # temporary until string.h is fixed
         KBUILD_CFLAGS += -ffreestanding
 
-        ifeq ($(CONFIG_STACKPROTECTOR),y)
-                ifeq ($(CONFIG_SMP),y)
+    ifeq ($(CONFIG_STACKPROTECTOR),y)
+        ifeq ($(CONFIG_SMP),y)
 			KBUILD_CFLAGS += -mstack-protector-guard-reg=fs -mstack-protector-guard-symbol=__stack_chk_guard
-                else
+        else
 			KBUILD_CFLAGS += -mstack-protector-guard=global
-                endif
         endif
+    endif
 else
         BITS := 64
         UTS_MACHINE := x86_64