Configure: added explicit ngx_binext to the linker output argument.

Unlike with GCC or MSVC, Clang linker doesn't auto-append ".exe" to the name
of the output binary when building on win32.

auto/make

diff --git a/auto/make b/auto/make
index 7ddd100..34c40cd 100644
--- a/auto/make
+++ b/auto/make
@@ -229,7 +229,7 @@
 binary:	$NGX_OBJS${ngx_dirsep}nginx$ngx_binext
 
 $NGX_OBJS${ngx_dirsep}nginx$ngx_binext:	$ngx_deps$ngx_spacer
-	\$(LINK) $ngx_long_start$ngx_binout$NGX_OBJS${ngx_dirsep}nginx$ngx_long_cont$ngx_objs$ngx_libs$ngx_link$ngx_main_link
+	\$(LINK) $ngx_long_start$ngx_binout$NGX_OBJS${ngx_dirsep}nginx$ngx_binext$ngx_long_cont$ngx_objs$ngx_libs$ngx_link$ngx_main_link
 	$ngx_rcc
 $ngx_long_end