kbuild: Prefer Kbuild as name of the kbuild files

The kbuild syntax is unique and does only have very few things in common with
usual Makefile syntax. So to avoid confusion make the filename 'Kbuild' be
the preferred name as replacement for 'Makefile'.
No global renaming planned to take place for now, but new stuff expected to use
the new 'Kbuild' filename.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

Documentation/kbuild/makefiles.txt

@@ -6,7 +6,7 @@ This document describes the Linux kernel Makefiles.
 
 	=== 1 Overview
 	=== 2 Who does what
-	=== 3 The kbuild Makefiles
+	=== 3 The kbuild files
 	   --- 3.1 Goal definitions
 	   --- 3.2 Built-in object goals - obj-y
 	   --- 3.3 Loadable module goals - obj-m
@@ -101,11 +101,14 @@ These people need to know about all aspects of the kernel Makefiles.
 This document is aimed towards normal developers and arch developers.
 
 
-=== 3 The kbuild Makefiles
+=== 3 The kbuild files
 
 Most Makefiles within the kernel are kbuild Makefiles that use the
 kbuild infrastructure. This chapter introduce the syntax used in the
 kbuild makefiles.
+The preferred name for the kbuild files is 'Kbuild' but 'Makefile' will
+continue to be supported. All new developmen is expected to use the
+Kbuild filename.
 
 Section 3.1 "Goal definitions" is a quick intro, further chapters provide
 more details, with real examples.

scripts/Makefile.build

@@ -10,7 +10,7 @@ __build:
 # Read .config if it exist, otherwise ignore
 -include .config
 
-include $(obj)/Makefile
+include $(if $(wildcard $(obj)/Kbuild), $(obj)/Kbuild, $(obj)/Makefile)
 
 include scripts/Makefile.lib
 

scripts/Makefile.clean

@@ -7,7 +7,7 @@ src := $(obj)
 .PHONY: __clean
 __clean:
 
-include $(obj)/Makefile
+include $(if $(wildcard $(obj)/Kbuild), $(obj)/Kbuild, $(obj)/Makefile)
 
 # Figure out what we need to build from the various variables
 # ==========================================================================