nginx: Fix compilation with LTO

When CONFIG_USE_LTO=y, the int-size detection script will fail because a
variable gets optimised out. Mark it as volatile to fix the issue.

Signed-off-by: Andreas Gnau <andreas.gnau@iopsys.eu>

net/nginx/patches/nginx/102-sizeof_test_fix.patch

@@ -4,7 +4,7 @@
  $NGX_INCLUDE_INTTYPES_H
  $NGX_INCLUDE_AUTO_CONFIG_H
  
-+char object_code_block[] = {
++volatile char object_code_block[] = {
 +	'\n', 'e', '4', 'V', 'A',
 +	'0', 'x', ('0' + sizeof($ngx_type)),
 +	'Y', '3', 'p', 'M', '\n'