kbuild: merge generic-asm-offsets.h and asm-offsets.h rules

The rules "cmd_generic-offsets" and "cmd_offsets" are almost the
same. (The difference is only the include guards.)
They can be merged.

This commit is mostly inspired by the following commit of Linux.

    commit 39664e2f3cdef98f42437e903159a6044a1d99d6
    Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
    Date:   Mon Jan 5 15:57:15 2015 +0900

        kbuild: merge bounds.h and asm-offsets.h rules

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Kbuild

@@ -4,19 +4,20 @@
 # 1) Generate generic-asm-offsets.h
 # 2) Generate asm-offsets.h
 
-#####
-# 1) Generate generic-asm-offsets.h
-
-generic-offsets-file := include/generated/generic-asm-offsets.h
-
-always  := $(generic-offsets-file)
-targets := $(generic-offsets-file) lib/asm-offsets.s
+# Default sed regexp - multiline due to syntax constraints
+define sed-y
+	"s:[[:space:]]*\.ascii[[:space:]]*\"\(.*\)\":\1:; \
+	/^->/{s:->#\(.*\):/* \1 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
+	s:->::; p;}"
+endef
 
-quiet_cmd_generic-offsets = GEN     $@
-define cmd_generic-offsets
+quiet_cmd_offsets = GEN     $@
+define cmd_offsets
 	(set -e; \
-	 echo "#ifndef __GENERIC_ASM_OFFSETS_H__"; \
-	 echo "#define __GENERIC_ASM_OFFSETS_H__"; \
+	 echo "#ifndef $2"; \
+	 echo "#define $2"; \
 	 echo "/*"; \
 	 echo " * DO NOT MODIFY."; \
 	 echo " *"; \
@@ -29,6 +30,14 @@ define cmd_generic-offsets
 	 echo "#endif" ) > $@
 endef
 
+#####
+# 1) Generate generic-asm-offsets.h
+
+generic-offsets-file := include/generated/generic-asm-offsets.h
+
+always  := $(generic-offsets-file)
+targets := $(generic-offsets-file) lib/asm-offsets.s
+
 # We use internal kbuild rules to avoid the "is up to date" message from make
 lib/asm-offsets.s: lib/asm-offsets.c FORCE
 	$(Q)mkdir -p $(dir $@)
@@ -36,7 +45,7 @@ lib/asm-offsets.s: lib/asm-offsets.c FORCE
 
 $(obj)/$(generic-offsets-file): lib/asm-offsets.s Kbuild
 	$(Q)mkdir -p $(dir $@)
-	$(call cmd,generic-offsets)
+	$(call cmd,offsets,__GENERIC_ASM_OFFSETS_H__)
 
 #####
 # 2) Generate asm-offsets.h
@@ -50,39 +59,12 @@ always  += $(offsets-file)
 targets += $(offsets-file)
 targets += arch/$(ARCH)/lib/asm-offsets.s
 
-
-# Default sed regexp - multiline due to syntax constraints
-define sed-y
-	"s:[[:space:]]*\.ascii[[:space:]]*\"\(.*\)\":\1:; \
-	/^->/{s:->#\(.*\):/* \1 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
-	s:->::; p;}"
-endef
-
 CFLAGS_asm-offsets.o := -DDO_DEPS_ONLY
 
-quiet_cmd_offsets = GEN     $@
-define cmd_offsets
-	(set -e; \
-	 echo "#ifndef __ASM_OFFSETS_H__"; \
-	 echo "#define __ASM_OFFSETS_H__"; \
-	 echo "/*"; \
-	 echo " * DO NOT MODIFY."; \
-	 echo " *"; \
-	 echo " * This file was generated by Kbuild"; \
-	 echo " *"; \
-	 echo " */"; \
-	 echo ""; \
-	 sed -ne $(sed-y) $<; \
-	 echo ""; \
-	 echo "#endif" ) > $@
-endef
-
 # We use internal kbuild rules to avoid the "is up to date" message from make
 arch/$(ARCH)/lib/asm-offsets.s: arch/$(ARCH)/lib/asm-offsets.c FORCE
 	$(Q)mkdir -p $(dir $@)
 	$(call if_changed_dep,cc_s_c)
 
 $(obj)/$(offsets-file): arch/$(ARCH)/lib/asm-offsets.s Kbuild
-	$(call cmd,offsets)
+	$(call cmd,offsets,__ASM_OFFSETS_H__)