pkg/arch: Set name/email in local git config

We run the PKGBUILD as 'nobody', so we can't set global git config
options. So set local ones instead.

pkg/arch/kernel/PKGBUILD

@@ -78,8 +78,8 @@ prepare() {
   echo "${pkgbase#linux}" > localversion.20-pkgname
 
   # setup git
-  git config --global user.email "surfacebot@users.noreply.github.com"
-  git config --global user.name "surfacebot"
+  git config --local user.email "surfacebot@users.noreply.github.com"
+  git config --local user.name "surfacebot"
 
   local src
   for src in "${source[@]}"; do