introduce option to time assert()s

. remove a few asserts in the kernel and 64bi library
    that are not compatible with the timing code
  . change the TIME_BLOCKS code a little to work in-kernel

kernel/arch/i386/exception.c

@@ -24,8 +24,6 @@ PRIVATE void pagefault( struct proc *pr,
 	message m_pagefault;
 	int err;
 
-	assert(frame);
-
 	pagefaultcr2 = read_cr2();
 
 #if 0
@@ -33,10 +31,6 @@ PRIVATE void pagefault( struct proc *pr,
 		pr->p_endpoint, pagefaultcr2, pr->p_seg.p_cr3, read_cr3());
 #endif
 
-	if(pr->p_seg.p_cr3) {
-		assert(pr->p_seg.p_cr3 == read_cr3());
-	}
-
 	in_physcopy = (frame->eip > (vir_bytes) phys_copy) &&
 	   (frame->eip < (vir_bytes) phys_copy_fault);
 
@@ -81,8 +75,6 @@ PRIVATE void pagefault( struct proc *pr,
 	}
 
 	/* Don't schedule this process until pagefault is handled. */
-	assert(pr->p_seg.p_cr3 == read_cr3());
-	assert(!RTS_ISSET(pr, RTS_PAGEFAULT));
 	RTS_SET(pr, RTS_PAGEFAULT);
 
 	/* tell Vm about the pagefault */