BaseTools: Remove the deprecated hash_key()

Replace "has_key()" with "in" to be compatible with python3.
Based on "futurize -f lib2to3.fixes.fix_has_key"

Contributed-under: TianoCore Contribution Agreement 1.1
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Yonghong Zhu <yonghong.zhu@intel.com>

BaseTools/Source/Python/build/build.py

@@ -77,7 +77,7 @@ TmpTableDict = {}
 #   Otherwise, False is returned
 #
 def IsToolInPath(tool):
-    if os.environ.has_key('PATHEXT'):
+    if 'PATHEXT' in os.environ:
         extns = os.environ['PATHEXT'].split(os.path.pathsep)
     else:
         extns = ('',)