Modified grep syntax in build scripts

[arango]

Changed the grep syntax in all build script which evaluates a Perl regular expression. This syntax is different in various operating system and we may get errors.

In build.sh we now have:

      if (`echo $1 | grep '^[0-9]\+$'` != "" ) then
        ...
      endif

instead of

      if (`echo $1 | grep -P '^\d+$'` != "" ) then
        ...
      endif

In build.bash we now have:

       test=`echo $1 | grep '^[0-9]\+$'`

instead of

       test=`echo $1 | grep -P '^\d+$'`