X tcpu: Don't depend on running tests with cwd = .../go/neo/t/

Previously when the code was trying to load testdata/ files with
different CWD it was failing with something like

	testdata/zlib/wczdata: no such file or directory.

Fix it by constructing testdata path relative to __file__ of
corresponding source.

go/neo/t/tcpu.go

@@ -33,10 +33,12 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"path/filepath"
 	"strconv"
 	"testing"
 	"time"
 
+	"lab.nexedi.com/kirr/go123/my"
 	"lab.nexedi.com/kirr/neo/go/neo/internal/xzlib"
 )
 
@@ -106,8 +108,10 @@ func xreadfile(path string) []byte {
 	return data
 }
 
+var __dir__ = filepath.Dir(my.File())
+
 func BenchmarkUnzlib(b *testing.B, zfile string) {
-	zdata := xreadfile(fmt.Sprintf("testdata/zlib/%s", zfile))
+	zdata := xreadfile(fmt.Sprintf("%s/testdata/zlib/%s", __dir__, zfile))
 
 	b.ResetTimer()
 

go/neo/t/tcpu.py

@@ -28,6 +28,7 @@ import tzodb
 import zlib
 from time import time
 from math import ceil, log10
+from os.path import dirname
 
 # fmtsize formats size in human readable form
 _unitv = "BKMGT" # (2^10)^i represents by corresponding char suffix
@@ -132,8 +133,11 @@ def readfile(path):
     with open(path, 'r') as f:
         return f.read()
 
+
+__dir__ = dirname(__file__)
+
 def bench_unzlib(b, zfile):
-    zdata = readfile('testdata/zlib/%s' % zfile)
+    zdata = readfile('%s/testdata/zlib/%s' % (__dir__, zfile))
     b.reset_timer()
 
     n = b.N