[v3] Fix race condition in libstdc++-v3/configure.ac

[Paolo Bonzini]

On 08/31/2009 11:26 PM, Ralf Wildenhues wrote:
> I wasn't quite sure whether the 'cd include&&  make' is necessary each
> time include/Makefile is changed, or only when config.status is invoked
> without arguments (i.e., after configure runs).  The patch assumes the
> latter and introduces a 'generate-headers' tag for this.

It seems safest to invoke "make -C include pch_build=" on every 
include/Makefile change, and leave the pch to be created by the 
recursive make invocation.  In principle, the task of include/Makefile 
could be done all by AC_CONFIG_LINKS, but not pch creation.

Also, you probably need to modify the configure-[+prefix+][+module+] 
definition in the toplevel, and add a : $(MAKE) there.

Paolo