fmt: remove math package dependency and avoid float operations

Remove floating point comparisons and rely only on the information
directly provided by appendFloat.
Make restoring the zero padding flag explicit instead of using a defer.
Rearrange some case distinctions to remove duplicated code.
Add more test cases for zero padded floating point numbers with sign.

benchmark                   old ns/op     new ns/op     delta
BenchmarkSprintfFloat-4     187           180           -3.74%

Change-Id: Ifa2ae85257909f40b1b18118c92b516933271729
Reviewed-on: https://go-review.googlesource.com/19721
Reviewed-by: Rob Pike <r@golang.org>

0 files changed, 0 insertions, 0 deletions