rectangle-math.mac -> tap-out:  Move expect()
tap-out:  Add EXPECT_NULL() macro
base/* tests:  Use EXPECT() macro
lamp/Genie/t:  Use EXPECT() macro
t/alloca-longjmp:  Just pass TODO test on PowerPC

This drops the TODO designation in favor of marking the test as passing.
The motivation is to stop using ok_if(), and a variant of EXPECT() which
supports TODO doesn't exist yet.  A further justification is that fixing
alloca/longjmp to work on PowerPC isn't exactly on my TODO list.
lamp/Kerosene/t:  Use EXPECT() macro
test-pread:  Use EXPECT() macro
mac/* tests:  Use EXPECT() macro
posix/command/t:  Use EXPECT() macro
relix/t:  Use EXPECT() macro
sys/t/m68k:  Use EXPECT() macro
sys/t/macos:  Use EXPECT() macro
v68k/t:  Use EXPECT() macro
Merge branch 'tap-expect'