On some platforms (for example, x86_64), the first call to
`objc_autoreleaseReturnValue` will always autorelease because it would
fail to verify the instruction sequence in the caller. On x86_64
certain PLT entries would be still pointing to the resolver function,
and sniffing the call sequence would fail.
This change adds a "warmup" return-autoreleased sequence to the test
harness.
rdar://18385128
Swift SVN r22127
the type
Printing Float32 with %0.15g not only wastes screen space, but also causes
confusion for users, and pretends that a Float32 has more precision than it
actually does.
rdar://18043123
Swift SVN r21435
