all: single space after period

Follow CL 20022 and consistently use single space after a period in
documentation.

Generated with:

$ perl -i -npe 's,^(\s*// .+[a-z]\.)  +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.)  +([A-Z])')

Change-Id: Ia29ad823668f060e81293e848a79fc4b4857d94b
Reviewed-on: https://go-review.googlesource.com/73530
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

unix/syscall_linux.go

@@ -255,7 +255,7 @@ func Getgroups() (gids []int, err error) {
 		return nil, nil
 	}
 
-	// Sanity check group count.  Max is 1<<16 on Linux.
+	// Sanity check group count. Max is 1<<16 on Linux.
 	if n < 0 || n > 1<<20 {
 		return nil, EINVAL
 	}
@@ -290,8 +290,8 @@ type WaitStatus uint32
 // 0x7F (stopped), or a signal number that caused an exit.
 // The 0x80 bit is whether there was a core dump.
 // An extra number (exit code, signal causing a stop)
-// is in the high bits.  At least that's the idea.
-// There are various irregularities.  For example, the
+// is in the high bits. At least that's the idea.
+// There are various irregularities. For example, the
 // "continued" status is 0xFFFF, distinguishing itself
 // from stopped via the core dump bit.
 
@@ -1023,7 +1023,7 @@ func ptracePeek(req int, pid int, addr uintptr, out []byte) (count int, err erro
 
 	var buf [sizeofPtr]byte
 
-	// Leading edge.  PEEKTEXT/PEEKDATA don't require aligned
+	// Leading edge. PEEKTEXT/PEEKDATA don't require aligned
 	// access (PEEKUSER warns that it might), but if we don't
 	// align our reads, we might straddle an unmapped page
 	// boundary and not get the bytes leading up to the page