compile all manpages in parallel!

Signed-off-by: Nico Schottelius <nico@kr.ethz.ch>

build.sh

@@ -51,9 +51,10 @@ case "$1" in
    manbuild)
       for src in ${MAN1DSTDIR}/*.text ${MAN7DSTDIR}/*.text; do
          echo "Compiling manpage and html for $src"
-         $A2XM "$src"
+         $A2XM "$src" &
-         $A2XH "$src"
+         $A2XH "$src" &
       done
+      wait
    ;;
 
    mandirs)