Replace static numpy allocator by function containing static.

That enables the numpy code to be its own library, in case
some users want to (e.g. CLIF library).

modules/core/misc/python/pyopencv_umat.hpp

@@ -28,7 +28,7 @@ static void* cv_UMat_context()
 static Mat cv_UMat_get(const UMat* _self)
 {
     Mat m;
-    m.allocator = &g_numpyAllocator;
+    m.allocator = &GetNumpyAllocator();
     _self->copyTo(m);
     return m;
 }

modules/python/src2/cv2_convert.cpp

@@ -56,7 +56,7 @@ bool pyopencv_to(PyObject* o, Mat& m, const ArgInfo& info)
     if(!o || o == Py_None)
     {
         if( !m.data )
-            m.allocator = &g_numpyAllocator;
+            m.allocator = &GetNumpyAllocator();
         return true;
     }
 
@@ -298,14 +298,14 @@ bool pyopencv_to(PyObject* o, Mat& m, const ArgInfo& info)
 #endif
 
     m = Mat(ndims, size, type, PyArray_DATA(oarr), step);
-    m.u = g_numpyAllocator.allocate(o, ndims, size, type, step);
+    m.u = GetNumpyAllocator().allocate(o, ndims, size, type, step);
     m.addref();
 
     if( !needcopy )
     {
         Py_INCREF(o);
     }
-    m.allocator = &g_numpyAllocator;
+    m.allocator = &GetNumpyAllocator();
 
     return true;
 }
@@ -316,9 +316,9 @@ PyObject* pyopencv_from(const cv::Mat& m)
     if( !m.data )
         Py_RETURN_NONE;
     cv::Mat temp, *p = (cv::Mat*)&m;
-    if(!p->u || p->allocator != &g_numpyAllocator)
+    if(!p->u || p->allocator != &GetNumpyAllocator())
     {
-        temp.allocator = &g_numpyAllocator;
+        temp.allocator = &GetNumpyAllocator();
         ERRWRAP2(m.copyTo(temp));
         p = &temp;
     }

modules/python/src2/cv2_numpy.cpp

@@ -6,8 +6,6 @@
 #include "cv2_numpy.hpp"
 #include "cv2_util.hpp"
 
-NumpyAllocator g_numpyAllocator;
-
 using namespace cv;
 
 UMatData* NumpyAllocator::allocate(PyObject* o, int dims, const int* sizes, int type, size_t* step) const

modules/python/src2/cv2_numpy.hpp

@@ -18,7 +18,7 @@ class NumpyAllocator : public cv::MatAllocator
     const cv::MatAllocator* stdAllocator;
 };
 
-extern NumpyAllocator g_numpyAllocator;
+inline NumpyAllocator& GetNumpyAllocator() {static NumpyAllocator gNumpyAllocator;return gNumpyAllocator;}
 
 //======================================================================================================================