When I was writing patch 4/4 in callfuncs.exp, a fatal fail will make
the rest of tests failed as well.

In this patch, some code is moved to proc rerun_and_prepare, which is
called some times at the beginning of each tests.  Also, fetch registers
before each test starts, and then, compare with the register state after
test is done.

This patch is not about _Complex type testing.  With this patch, test
result of patch 4/4 looks more reasonable.

-- 
Yao (齐尧)