Improve fix against -dirty string in make kernelrelease

Do not remove .git directory because it cause successive call to makepkg to
not work. Use .scmversion file instead.

PKGBUILD

@@ -36,14 +36,15 @@ prepare() {
 	msg2 'Setting kernel suffix'
 	sed -i "s|CONFIG_LOCALVERSION=.*|CONFIG_LOCALVERSION=\"${pkgname#linux*}\"|g" .config
 
-  # remove git informations
-  # these info will be used by make kernelrelease and produce wrong information
-  # because ownership has fakely be changed by fakeroot during packaging.
-  rm -rf .git
-
   # define current build version
   msg2 'Setting kernel build version'
   echo "$(($pkgrel - 1 ))" > .version
+
+  # no scm version
+  # this prevent an issue with “make kernelrelease” which add -dirty to version
+  # because ownership of git files has fakely been changed by fakeroot when
+  # called from makepkg
+  echo '' > .scmversion
 }
 
 build() {