Fix: round function is not provided by libc.math on all platforms

skimage/transform/_hough_transform.pyx

@@ -2,7 +2,7 @@ cimport cython
 import numpy as np
 cimport numpy as np
 from random import randint
-from libc.math cimport abs, fabs, sqrt, ceil, floor, round
+from libc.math cimport abs, fabs, sqrt, ceil, floor
 from libc.stdlib cimport rand
 
 
@@ -13,6 +13,10 @@ cdef double PI_2 = 1.5707963267948966
 cdef double NEG_PI_2 = -PI_2
 
 
+cdef inline int round(double r):
+    return <int>((r + 0.5) if (r > 0.0) else (r - 0.5))
+
+
 @cython.boundscheck(False)
 def _hough(np.ndarray img, np.ndarray[ndim=1, dtype=np.double_t] theta=None):