Fix external modules compilation since 4.14.x

PKGBUILD

@@ -9,7 +9,7 @@ arch=('x86_64')
 license=('GPL2')
 url='http://www.kernel.org'
 options=('!strip')
-makedepends=('kmod' 'git' 'make' 'gcc' 'bc' 'sed')
+makedepends=('glibc' 'libelf' 'kmod' 'git' 'make' 'gcc' 'bc' 'sed')
 depends=('linux-firmware' 'kernel-install-hook')
 install=linux-seblu.install
 _repourl='git+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git'
@@ -200,6 +200,11 @@ install_sources() {
     [[ "${i##*/}" != x86 ]] && rm -rf "$i"
   done
 
+  # add objtool for external module building when enabled VALIDATION_STACK option
+  # this is adding dependencty to glibc and libelf to the kernel package
+  install -d "$kernsrc/tools/objtool"
+  cp tools/objtool/objtool "$kernsrc/tools/objtool"
+
   # fix permissions
   chown -R root:root "$kernsrc"
   find "$kernsrc" -type d -exec chmod 755 {} \;