BaseTools: Handle the bytes and str difference

Deal with bytes and str is different, remove the unicode(),
correct open file parameter.
Using utcfromtimestamp instead of fromtimestamp.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/AutoGen/GenMake.py

@@ -1038,17 +1038,21 @@ cleanlib:
                 CurrentFileDependencyList = DepDb[F]
             else:
                 try:
-                    Fd = open(F.Path, 'r')
+                    Fd = open(F.Path, 'rb')
+                    FileContent = Fd.read()
+                    Fd.close()
                 except BaseException as X:
                     EdkLogger.error("build", FILE_OPEN_FAILURE, ExtraData=F.Path + "\n\t" + str(X))
-
-                FileContent = Fd.read()
-                Fd.close()
                 if len(FileContent) == 0:
                     continue
 
                 if FileContent[0] == 0xff or FileContent[0] == 0xfe:
-                    FileContent = unicode(FileContent, "utf-16")
+                    FileContent = FileContent.decode('utf-16')
+                else:
+                    try:
+                        FileContent = str(FileContent)
+                    except:
+                        pass
                 IncludedFileList = gIncludePattern.findall(FileContent)
 
                 for Inc in IncludedFileList: