kbuild: add ability to make source rpm buildable using koji

Changes:
- added new target 'srcrpm-pkg' to generate source rpm
- added required build tools to spec file
- removed locally compiled host tools to force their re-compile

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Jonathan Toppins <jtoppins@redhat.com>
Acked-by: Íñigo Huguet <ihuguet@redhat.com>
Tested-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

scripts/package/mkspec

@@ -33,6 +33,8 @@ EXCLUDES="$RCS_TAR_IGNORE --exclude=*vmlinux* --exclude=*.mod \
 --exclude=*.o --exclude=*.ko --exclude=*.cmd --exclude=Documentation \
 --exclude=.config.old --exclude=.missing-syscalls.d --exclude=*.s"
 
+test -n "$LOCALVERSION" && MAKE="$MAKE LOCALVERSION=$LOCALVERSION"
+
 # We can label the here-doc lines for conditional output to the spec file
 #
 # Labels:
@@ -49,6 +51,9 @@ sed -e '/^DEL/d' -e 's/^\t*//' <<EOF
 	URL: https://www.kernel.org
 $S	Source: kernel-$__KERNELRELEASE.tar.gz
 	Provides: $PROVIDES
+$S	BuildRequires: bc binutils bison dwarves elfutils-libelf-devel flex
+$S	BuildRequires: gcc make openssl openssl-devel perl python3 rsync
+
 	# $UTS_MACHINE as a fallback of _arch in case
 	# /usr/lib/rpm/platform/*/macros was not included.
 	%define _arch %{?_arch:$UTS_MACHINE}
@@ -80,6 +85,8 @@ $S$M	against the $__KERNELRELEASE kernel package.
 $S$M
 $S	%prep
 $S	%setup -q
+$S	rm -f scripts/basic/fixdep scripts/kconfig/conf
+$S	rm -f tools/objtool/{fixdep,objtool}
 $S
 $S	%build
 $S	$MAKE %{?_smp_mflags} KBUILD_BUILD_VERSION=%{release}