Fix __sglue inititialization

Do not initialize __sglue with the FILE objects of _GLOBAL_REENT to avoid a
double use in the !_REENT_SMALL and !_REENT_GLOBAL_STDIO_STREAMS configurations
which didn't use a thread-specific reentrancy structure.

newlib/libc/stdio/findfp.c

@@ -41,11 +41,7 @@ const struct __sFILE_fake __sf_fake_stderr =
 __FILE __sf[3];
 struct _glue __sglue = {NULL, 3, &__sf[0]};
 #else
-#ifdef _REENT_SMALL
 struct _glue __sglue = {NULL, 0, NULL};
-#else
-struct _glue __sglue = {NULL, 3, &_GLOBAL_REENT->__sf[0]};
-#endif
 #endif
 
 #ifdef _STDIO_BSD_SEMANTICS