adding support for google performance tools to the build sytem, it can be enabled...

adding support for google performance tools to the build sytem, it can be enabled at configure with
--with-google-perftools

to use it on ubuntu, you need to install packages google-perftools and libgoogle-perftools0

to run the profiling of the heap, you can run it for example with

HEAPPROFILE=/tmp/profile ./builds/bin/cvc4 test/regress/regress0/lemmas/clocksynchro_5clocks.main_invar.base.smt

this will create some files  /tmp/profile* that you can then

to get the pdf of the profile you can then run

google-pprof --pdf ./builds/bin/cvc4 /tmp/profile.0001.heap > profile.pdf

or for other options check http://goog-perftools.sourceforge.net/doc/