xbps-src: relax check for writable hostdir.

buildbot does not like it.

xbps-src

@@ -503,9 +503,6 @@ fi
 if [ -d "$XBPS_MASTERDIR" -a ! -w "$XBPS_MASTERDIR" ]; then
     echo "ERROR: can't write to masterdir $XBPS_MASTERDIR."
     exit 1
-elif [ -d "$XBPS_HOSTDIR" -a ! -w "$XBPS_HOSTDIR" ]; then
-    echo "ERROR: can't write to hostdir: $XBPS_HOSTDIR."
-    exit 1
 fi
 
 # Try using chroot-git then git from the host system