kbuild: install all headers when arch is changed

We see some header files that are selected dependent on
the actual architecture so force a reinstallation
of all header files when the arch changes.
This slows down "make headers_check_all" but then
we better reflect reality.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/Makefile.headersinst

@@ -43,8 +43,9 @@ printdir = $(patsubst $(INSTALL_HDR_PATH)/%/,%,$(dir $@))
 
 quiet_cmd_install = INSTALL $(printdir) ($(words $(all-files))\
                             file$(if $(word 2, $(all-files)),s))
-      cmd_install = $(PERL) $< $(srctree)/$(obj) $(install) $(header-y); \
-                    $(PERL) $< $(objtree)/$(obj) $(install) $(objhdr-y); \
+      cmd_install = \
+        $(PERL) $< $(srctree)/$(obj) $(install) $(SRCARCH) $(header-y); \
+        $(PERL) $< $(objtree)/$(obj) $(install) $(SRCARCH) $(objhdr-y); \
         touch $@
 
 quiet_cmd_remove = REMOVE  $(unwanted)

scripts/headers_install.pl

@@ -3,9 +3,12 @@
 # headers_install prepare the listed header files for use in
 # user space and copy the files to their destination.
 #
-# Usage: headers_install.pl odir installdir [files...]
-# odir:    dir to open files
-# install: dir to install the files
+# Usage: headers_install.pl readdir installdir arch [files...]
+# readdir:    dir to open files
+# installdir: dir to install the files
+# arch:       current architecture
+#             arch is used to force a reinstallation when the arch
+#             changes because kbuild then detect a command line change.
 # files:      list of files to check
 #
 # Step in preparation for users space:
@@ -16,7 +19,7 @@
 use strict;
 use warnings;
 
-my ($readdir, $installdir, @files) = @ARGV;
+my ($readdir, $installdir, $arch, @files) = @ARGV;
 
 my $unifdef = "scripts/unifdef -U__KERNEL__";