Make custom printf independent from pending runtime errors

[Garados007]

We already use a small trick which performs tasks that can have new runtime errors for GetWavePointer:

igortest/procedures/igortest-utils.ipf

Lines 356 to 357 in 080690c

	Make/FREE/T/N=2 address
	MultiThread address = GetWavePointer_Impl(wv)

Using this for printf, we can allow pending runtime errors from the test case and create new messages at the same time. To prevent the double execution, we can check in the called function if it was called a second time and just return.