Win32: properly enabled select on Windows.

Previously, select was compiled in by default, but the NGX_HAVE_SELECT
macro was not set, resulting in iocp being used by default unless
the "--with-select_module" configure option was explicitly specified.
Since the iocp module is not finished and does not work properly, this
effectively meant that the "--with-select_module" option was mandatory.

With the change NGX_HAVE_SELECT is properly set, making "--with-select_module"
optional.  Accordingly, it is removed from misc/GNUmakefile win32 target.

auto/os/win32

@@ -34,6 +34,7 @@ EVENT_MODULES="$EVENT_MODULES $IOCP_MODULE"
 EVENT_FOUND=YES
 
 if [ $EVENT_SELECT = NO ]; then
+    have=NGX_HAVE_SELECT . auto/have
     CORE_SRCS="$CORE_SRCS $SELECT_SRCS"
     EVENT_MODULES="$EVENT_MODULES $SELECT_MODULE"
 fi

misc/GNUmakefile

@@ -65,7 +65,6 @@ win32:
 		--with-cc-opt=-DFD_SETSIZE=1024				\
 		--with-pcre=$(OBJS)/lib/$(PCRE)				\
 		--with-zlib=$(OBJS)/lib/$(ZLIB)				\
-		--with-select_module					\
 		--with-http_v2_module					\
 		--with-http_realip_module				\
 		--with-http_addition_module				\