- crt: Use ANSI C types

- math.h: Move nonstandard inline using nonstandard function into nonstandard group
- crtdefs.h: Don't disable non-ANSI C definitions for MSVC only -- the behaviour should be the same for all compilers, so always disable them -- fixes various msvc build errors introduced by 42369.

svn path=/trunk/; revision=42418

reactos/lib/sdk/crt/stdlib/_exit.c

@@ -19,7 +19,7 @@ void exit(int status)
     djgpp_first_dtor[i]();
 */
   /* in case the program set it this way */
-  _setmode(0, O_TEXT);
+  _setmode(0, _O_TEXT);
   _atexit_cleanup();
   _exit(status);
   for(;;);