Currently, it is not possible compile OpenCV 4.5.4 using Clang 7.0.1 + musl due to__WORDSIZE not being defined. As a consequence, the following error is issued:

opencv_contrib/modules/wechat_qrcode/src/zxing/common/bitarray.cpp:18:5: warning: '__WORDSIZE' is not defined, evaluates to 0 [-Wundef]#if __WORDSIZE == 64    ^opencv_contrib/modules/wechat_qrcode/src/zxing/common/bitarray.cpp:21:23: error: typedef redefinition with different types ('long long' vs 'long')typedef long long int int64_t;                      ^<...>/sysroots/core2-64-<snip>-linux-musl/usr/include/bits/alltypes.h:152:25: note: previous definition is heretypedef signed _Int64   int64_t;                        ^1 warning and 1 error generated.

Since theint64_t typedef is unused in the translation unit anyway, we can simply remove the definition.

Pull Request Readiness Checklist

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or other license that is incompatible with OpenCV
• The PR is proposed to proper branch
• There is reference to original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake

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