fix(os): Find /etc/makepkg.conf both with and without chroot (#1)

setup.sh

@@ -388,9 +388,14 @@ function create_unpriv_user () {
 }
 
 function unleash_makepkg () {
+    local path_prefix
+    path_prefix='/mnt'
+    if we_are_changerooted; then
+        path_prefix=''
+    fi
     sed -ri \
         -e 's'$'\x1''^(#?(MAKEFLAGS=))[^\r\n\f]*'$'\x1''\2"-j$(nproc --ignore 1)"'$'\x1''g' \
-        '/mnt/etc/makepkg.conf'
+        "${path_prefix}"'/etc/makepkg.conf'
 }
 
 function get_aur_helper () {