Added support for the number of jobs during a make.

Added support for the number of jobs during a make.

Moved common functions in a new android-common.el file.
Declared a customizable variable to control the number
of jobs used during the make process.

In android-compile, call compile interactively to honor
 the compile-read-command feature to give the user the opportunity
to edit the command (e.g add the snod target)