math: remove the leading F from Fabs etc.
The letter is a holdover from C and unnecessary in Go.
Gofix module included.
Fixes #2306.

R=golang-dev, gri, dsymonds
CC=golang-dev
https://golang.org/cl/5158043
diff --git a/src/pkg/rand/rand_test.go b/src/pkg/rand/rand_test.go
index 3ebc114..f997ff5 100644
--- a/src/pkg/rand/rand_test.go
+++ b/src/pkg/rand/rand_test.go
@@ -30,11 +30,11 @@
 }
 
 func nearEqual(a, b, closeEnough, maxError float64) bool {
-	absDiff := math.Fabs(a - b)
+	absDiff := math.Abs(a - b)
 	if absDiff < closeEnough { // Necessary when one value is zero and one value is close to zero.
 		return true
 	}
-	return absDiff/max(math.Fabs(a), math.Fabs(b)) < maxError
+	return absDiff/max(math.Abs(a), math.Abs(b)) < maxError
 }
 
 var testSeeds = []int64{1, 1754801282, 1698661970, 1550503961}