erts/configure.in: Remove test for reversed setvbuf() arguments

The test is not needed, because no code tests whether SETVBUF_REVERSED
is defined.

Furthermore, AC_FUNC_SETVBUF_REVERSED is now documented like this:

Do nothing. Formerly, this macro checked whether setvbuf takes the
buffering type as its second argument and the buffer pointer as the
third, instead of the other way around, and defined
SETVBUF_REVERSED. However, the last systems to have the problem were
those based on SVR2, which became obsolete in 1987, and the macro is
no longer needed.

erts/autoconf/win32.config.cache.static

@@ -96,7 +96,6 @@ ac_cv_func_sbrk=${ac_cv_func_sbrk=no}
 ac_cv_func_select=${ac_cv_func_select=no}
 ac_cv_func_setlocale=${ac_cv_func_setlocale=yes}
 ac_cv_func_setsid=${ac_cv_func_setsid=no}
-ac_cv_func_setvbuf_reversed=${ac_cv_func_setvbuf_reversed=yes}
 ac_cv_func_socket=${ac_cv_func_socket=no}
 ac_cv_func_strchr=${ac_cv_func_strchr=yes}
 ac_cv_func_strerror=${ac_cv_func_strerror=yes}

erts/configure.in

@@ -1792,11 +1792,6 @@ AC_CHECK_FUNCS([ieee_handler fpsetmask finite isnan isinf res_gethostbyname dlop
 
 AC_CHECK_DECLS([posix2time],,,[#include <time.h>])
 
-if test "X$host" = "Xwin32"; then
-	ac_cv_func_setvbuf_reversed=yes
-fi
-AC_FUNC_SETVBUF_REVERSED	
-
 disable_vfork=false
 if test "x$EMU_THR_LIB_NAME" != "x"; then
 	AC_MSG_CHECKING([if vfork is known to hang multithreaded applications])