build: adjustments for move from src/pkg to src

This CL adjusts code referring to src/pkg to refer to src.

Immediately after submitting this CL, I will submit
a change doing 'hg mv src/pkg/* src'.
That change will be too large to review with Rietveld
but will contain only the 'hg mv'.

This CL will break the build.
The followup 'hg mv' will fix it.

For more about the move, see golang.org/s/go14nopkg.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/134570043
diff --git a/src/pkg/math/sqrt.go b/src/pkg/math/sqrt.go
index 1bd4437..fdc8699 100644
--- a/src/pkg/math/sqrt.go
+++ b/src/pkg/math/sqrt.go
@@ -80,7 +80,7 @@
 //
 //
 // Notes:  Rounding mode detection omitted.  The constants "mask", "shift",
-// and "bias" are found in src/pkg/math/bits.go
+// and "bias" are found in src/math/bits.go
 
 // Sqrt returns the square root of x.
 //