Current code doesn't support floating point #define macros.
This CL compiles floats to a object file and retrive values from it.
That approach is the same work as we've already done for integers.
Updates #18720
Change-Id: I88b7ab174d0f73bda975cf90c5aeb797961fe034
Reviewed-on: https://go-review.googlesource.com/35511 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>