Fix 2 new sets of clang compiler warnings.

Fix issues that are flagged by -Wfloat-equal and -Wmissing-noreturn.
In the case of -Wfloat-equal the current cases in regular code are deliberate,
so the change is to silence the warning. For gtest code the appropriate fix is
to switch from EXPECT_EQ to EXPECT_(FLOAT|DOUBLE)_EQ.
The -Wmissing-noreturn warning isn't enabled due to a missing noreturn in
gtest. This issue has been reported to gtest.

Change-Id: Id84c70c21c542716c9ee0c41492e8ff8788c4ef8