BUG, BLD: Fix cast long double and double warnings(C)/errors(C++)

  These errors/warnings occurs when sizeof(long double) == sizeof(double).

Author: seiko2plus

numpy/core/include/numpy/npy_common.h

@@ -359,12 +359,11 @@ typedef unsigned char npy_bool;
 
 
 #if NPY_SIZEOF_LONGDOUBLE == NPY_SIZEOF_DOUBLE
-        typedef double npy_longdouble;
         #define NPY_LONGDOUBLE_FMT "g"
 #else
-        typedef long double npy_longdouble;
         #define NPY_LONGDOUBLE_FMT "Lg"
 #endif
+typedef long double npy_longdouble;
 
 #ifndef Py_USING_UNICODE
 #error Must use Python with unicode enabled.