kbuild: make gcc -align options .config-settable

With all alignment options set to 1 (minimum alignment),
I've got 5% smaller vmlinux compared to one built with
default code alignment.
Original implementation altered to use cc-option-align by sam.

From: Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Makefile

@@ -503,6 +503,13 @@ else
 CFLAGS		+= -O2
 endif
 
+#Add align options if CONFIG_CC_* is not equal to 0
+add-align = $(if $(filter-out 0,$($(1))),$(cc-option-align)$(2)=$($(1)))
+CFLAGS		+= $(call add-align,CONFIG_CC_ALIGN_FUNCTIONS,-functions)
+CFLAGS		+= $(call add-align,CONFIG_CC_ALIGN_LABELS,-labels)
+CFLAGS		+= $(call add-align,CONFIG_CC_ALIGN_LOOPS,-loops)
+CFLAGS		+= $(call add-align,CONFIG_CC_ALIGN_JUMPS,-jumps)
+
 ifdef CONFIG_FRAME_POINTER
 CFLAGS		+= -fno-omit-frame-pointer
 else

init/Kconfig

@@ -303,6 +303,43 @@ config SHMEM
 	  option replaces shmem and tmpfs with the much simpler ramfs code,
 	  which may be appropriate on small systems without swap.
 
+config CC_ALIGN_FUNCTIONS
+	int "Function alignment"
+	default 0
+	help
+	  Align the start of functions to the next power-of-two greater than n,
+	  skipping up to n bytes.  For instance, 32 aligns functions
+	  to the next 32-byte boundary, but 24 would align to the next
+	  32-byte boundary only if this can be done by skipping 23 bytes or less.
+	  Zero means use compiler's default.
+
+config CC_ALIGN_LABELS
+	int "Label alignment"
+	default 0
+	help
+	  Align all branch targets to a power-of-two boundary, skipping
+	  up to n bytes like ALIGN_FUNCTIONS.  This option can easily
+	  make code slower, because it must insert dummy operations for
+	  when the branch target is reached in the usual flow of the code.
+	  Zero means use compiler's default.
+
+config CC_ALIGN_LOOPS
+	int "Loop alignment"
+	default 0
+	help
+	  Align loops to a power-of-two boundary, skipping up to n bytes.
+	  Zero means use compiler's default.
+
+config CC_ALIGN_JUMPS
+	int "Jump alignment"
+	default 0
+	help
+	  Align branch targets to a power-of-two boundary, for branch
+	  targets where the targets can only be reached by jumping,
+	  skipping up to n bytes like ALIGN_FUNCTIONS.  In this case,
+	  no dummy operations need be executed.
+	  Zero means use compiler's default.
+
 endmenu		# General setup
 
 config TINY_SHMEM