fix(windows): CC crash on dtoa:fixup: fix(builtins): round(float[, n]) not to-even (ref #52)

Author: litlighilit

src/pylib/impure/math/dtoa-nim.c

@@ -1,8 +1,12 @@
 
+#include <stdlib.h>
+
 void ACQUIRE_DTOA_LOCK(int);
 void FREE_DTOA_LOCK(int);
 
 int dtoa_get_threadno(void);
 
+// avoid MinGW complaining conflict with strtod of <stdlib.h>
+#define strtod nimpylib_dtoa_strtod
 #include "./dtoa.c"
-
+#undef strtod

src/pylib/impure/math/dtoa.nim

@@ -69,14 +69,10 @@ char* dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
 ```]##
 
 proc strtod*(
-  s00: cstring, se: var cstring
-): cdouble{.importc: "strtod", cdecl.} ##[ ```c
+  s00: cstring, se: (var cstring)|(ptr cstring) # for `strtod(s, nil)`
+): cdouble{.importc: "nimpylib_dtoa_strtod", cdecl.} ##[ ```c
 double strtod(const char *s00, char **se)
 ```]##
 
-proc strtod*(
-  s00: cstring, se: ptr cstring
-): cdouble{.importc: "strtod", cdecl.} ## for `strtod(s, nil)`
-
 proc freedtoa*(s: cstring){.importc, cdecl.}