PreLoadBegin

Begin a segment of code that may be preloaded (run twice) to get accurate timings

	flag	- PETSC_TRUE to run twice, PETSC_FALSE to run once, may be overridden with command line option -preload true or -preload false
	name	- name of first stage (lines of code timed separately with -log_summary) to be preloaded

void PreLoadBegin(PetscTruth flag,char *name);

     PreLoadBegin(PETSC_TRUE,"first stage);
       lines of code
       PreLoadStage("second stage");
       lines of code
     PreLoadEnd();

Notes: Only works in C/C++, not Fortran

Flags available within the macro.

	PetscPreLoadingUsed	- true if we are or have done preloading
	PetscPreLoadingOn	- true if it is CURRENTLY doing preload
	PreLoadIt	- 0 for the first computation (with preloading turned off it is only 0) 1 for the second
	PreLoadMax	- number of times it will do the computation, only one when preloading is turned on The first two variables are available throughout the program, the second two only between the PreLoadBegin() and PreLoadEnd()