Update to build.sh

[Miles Bader]

Johannes Engel <jcnengel at googlemail.com> writes:
> Are you sure that only the existence of a file called "configure" is 
> enough to run this instead of autogen.sh? AFAIK some changes require a 
> new run of autogen.sh.

Does xorg use automake?  With automake-generated Makefiles (and some
non-automake generated Makefiles of course), the next make run should
re-generate/re-run the configure script if necessary, so it's generally
"ok" to use a slightly out-of-date configure.

-Miles

-- 
Carefully crafted initial estimates reward you not only with
reduced computational effort, but also with understanding and
increased self-esteem.         -- Numerical methods in C,
  Chapter 9. "Root Finding and Nonlinear Sets of Equations"