Temporary hack to fix build regression with Scikit-build 0.17.3 and n…

…ewer.

setup.py

@@ -36,9 +36,14 @@ def main():
     ]
 
     python_version = cmaker.CMaker.get_python_version()
-    python_lib_path = (cmaker.CMaker.get_python_library(python_version) or "").replace(
-        "\\", "/"
-    )
+    python_lib_path = cmaker.CMaker.get_python_library(python_version) or ""
+    # HACK: For Scikit-build 0.17.3 and newer that returns None or empty sptring for PYTHON_LIBRARY in manylinux2014
+    # A small release related to PYTHON_LIBRARY handling changes in 0.17.2; scikit-build 0.17.3 returns an empty string from get_python_library if no Python library is present (like on manylinux), where 0.17.2 returned None, and previous versions returned a non-existent path. Note that adding REQUIRED to find_package(PythonLibs will fail, but it is incorrect (you must not link to libPython.so) and was really just injecting a non-existent path before.
+    # TODO: Remove the hack when the issue is handled correctly in main OpenCV CMake.
+    if python_lib_path == "":
+        python_lib_path = "libpython%sm.a" % python_version
+    python_lib_path = python_lib_path.replace("\\", "/")
+
     python_include_dir = cmaker.CMaker.get_python_include_dir(python_version).replace(
         "\\", "/"
     )