Move PyBytes_RESIZE macro to compat_ext

Provide this macro in one place and `cimport` it everywhere else.

Author: jakirkham

numcodecs/blosc.pyx

@@ -15,19 +15,12 @@ from cpython.bytes cimport (
 )
 from cpython.memoryview cimport PyMemoryView_GET_BUFFER
 
-from .compat_ext cimport ensure_continguous_memoryview
+from .compat_ext cimport PyBytes_RESIZE, ensure_continguous_memoryview
 
 from .compat import ensure_contiguous_ndarray
 from .abc import Codec
 
 
-cdef extern from *:
-    """
-    #define PyBytes_RESIZE(b, n) _PyBytes_Resize(&b, n)
-    """
-    int PyBytes_RESIZE(object b, Py_ssize_t n) except -1
-
-
 cdef extern from "blosc.h":
     cdef enum:
         BLOSC_MAX_OVERHEAD,

numcodecs/compat_ext.pxd

@@ -1,4 +1,11 @@
 # cython: language_level=3
 
 
+cdef extern from *:
+    """
+    #define PyBytes_RESIZE(b, n) _PyBytes_Resize(&b, n)
+    """
+    int PyBytes_RESIZE(object b, Py_ssize_t n) except -1
+
+
 cpdef memoryview ensure_continguous_memoryview(obj)

numcodecs/lz4.pyx

@@ -13,20 +13,13 @@ from cpython.bytes cimport (
 )
 from cpython.memoryview cimport PyMemoryView_GET_BUFFER
 
-from .compat_ext cimport ensure_continguous_memoryview
+from .compat_ext cimport PyBytes_RESIZE, ensure_continguous_memoryview
 from ._utils cimport store_le32, load_le32
 
 from .compat import ensure_contiguous_ndarray
 from .abc import Codec
 
 
-cdef extern from *:
-    """
-    #define PyBytes_RESIZE(b, n) _PyBytes_Resize(&b, n)
-    """
-    int PyBytes_RESIZE(object b, Py_ssize_t n) except -1
-
-
 cdef extern from "lz4.h":
 
     const char* LZ4_versionString() nogil

numcodecs/zstd.pyx

@@ -11,19 +11,12 @@ from cpython.bytes cimport (
 )
 from cpython.memoryview cimport PyMemoryView_GET_BUFFER
 
-from .compat_ext cimport ensure_continguous_memoryview
+from .compat_ext cimport PyBytes_RESIZE, ensure_continguous_memoryview
 
 from .compat import ensure_contiguous_ndarray
 from .abc import Codec
 
 
-cdef extern from *:
-    """
-    #define PyBytes_RESIZE(b, n) _PyBytes_Resize(&b, n)
-    """
-    int PyBytes_RESIZE(object b, Py_ssize_t n) except -1
-
-
 cdef extern from "zstd.h":
 
     unsigned ZSTD_versionNumber() nogil