[CMake] ExternalProject feature regenerating the configure script

[Ashok Nalkund]

I noticed the following messages when I ran 'make VERBOSE=1 -d':

> <path to package>/build/src/package/Makefile.in'.
>     Prerequisite `<path to package>/build/src/package/aclocal.m4' is 
> newer than target `<path to package>/build/src/package/Makefile.in'.
>    Must remake target `<path to package>/build/src/package/Makefile.in'.
> Putting child 0x0156a7f0 (<path to 
> package>/build/src/mare/Makefile.in) PID 23029 on the chain.
> Live child 0x0156a7f0 (<path to package>/build/src/mare/Makefile.in) 
> PID 23029
>  cd <path to package>/build/src/mare && /bin/sh <path to 
> package>/build/src/mare/autotools/missing --run automake-1.11 --foreign
> aclocal.m4:17: warning: this file was generated for autoconf 2.68.

I'll dig into this more.

thanks,
ashok