This is an experimental commit to see whether any unit tests are transitively
depending on the #include <iomanip> directive from GoogleTest.
This include is responsible for ~0.45% of the preprocessing directives within
the LLVM project. From the C++ Compile Health Watchdog
we can see that this include adds 100-200ms of total compile time (20-30ms
preprocessing time).
This is now one of the single most expensive includes in LLVM.
Here this code is no longer correct after this change. But it's possible to move the setprecision call into the source file and not need a public include of <iomanip>. Here I have removed it since I don't have access to the source file of GoogleTest in LLVM and this is only a proof that the include is not needed anywhere else.