kbuild: rpm-pkg: fix binrpm-pkg breakage when O= is used

Zhenzhong Duan reported that running 'make O=/build/kernel binrpm-pkg'
failed with the following errors:

  Running 'make O=/build/kernel binrpm-pkg' failed with below two errors.

  Makefile:600: include/config/auto.conf: No such file or directory

  + cp make -C /mnt/root/kernel O=/build/kernel image_name make -f
  /mnt/root/kernel/Makefile ...
  cp: invalid option -- 'C'
  Try 'cp --help' for more information.

Prior to commit 80463f1b ("kbuild: add --include-dir flag only
for out-of-tree build"), both srctree and objtree were added to
--include-dir redundantly, and the wrong code 'make image_name'
was working by relying on that. Now, the potential issue that had
previously been hidden just showed up.

'make image_name' recurses to the generated $(objtree)/Makefile and
ends up with running in srctree, which is incorrect. It should be
invoked with '-f $srctree/Makefile' (or KBUILD_SRC=) to be executed
in objtree.

Fixes: 80463f1b ("kbuild: add --include-dir flag only for out-of-tree build")
Reported-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

scripts/package/mkspec

@@ -12,6 +12,7 @@
 # how we were called determines which rpms we build and how we build them
 if [ "$1" = prebuilt ]; then
 	S=DEL
+	MAKE="$MAKE -f $srctree/Makefile"
 else
 	S=
 fi
@@ -78,19 +79,19 @@ $S	%prep
 $S	%setup -q
 $S
 $S	%build
-$S	make %{?_smp_mflags} KBUILD_BUILD_VERSION=%{release}
+$S	$MAKE %{?_smp_mflags} KBUILD_BUILD_VERSION=%{release}
 $S
 	%install
 	mkdir -p %{buildroot}/boot
 	%ifarch ia64
 	mkdir -p %{buildroot}/boot/efi
-	cp \$(make image_name) %{buildroot}/boot/efi/vmlinuz-$KERNELRELEASE
+	cp \$($MAKE image_name) %{buildroot}/boot/efi/vmlinuz-$KERNELRELEASE
 	ln -s efi/vmlinuz-$KERNELRELEASE %{buildroot}/boot/
 	%else
-	cp \$(make image_name) %{buildroot}/boot/vmlinuz-$KERNELRELEASE
+	cp \$($MAKE image_name) %{buildroot}/boot/vmlinuz-$KERNELRELEASE
 	%endif
-$M	make %{?_smp_mflags} INSTALL_MOD_PATH=%{buildroot} KBUILD_SRC= modules_install
-	make %{?_smp_mflags} INSTALL_HDR_PATH=%{buildroot}/usr KBUILD_SRC= headers_install
+$M	$MAKE %{?_smp_mflags} INSTALL_MOD_PATH=%{buildroot} modules_install
+	$MAKE %{?_smp_mflags} INSTALL_HDR_PATH=%{buildroot}/usr headers_install
 	cp System.map %{buildroot}/boot/System.map-$KERNELRELEASE
 	cp .config %{buildroot}/boot/config-$KERNELRELEASE
 	bzip2 -9 --keep vmlinux