Pass PCRE_CASELESS to pcre_compile() for caseless matching.

Previously, we sometimes passed constant value 1 that happens to
match PCRE_CASELESS and thus was harmless.

src/http/ngx_http_core_module.c

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 80cf2d6..25d3dc9 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -3256,7 +3256,7 @@
 #if (NGX_HAVE_CASELESS_FILESYSTEM)
     rc.options = NGX_REGEX_CASELESS;
 #else
-    rc.options = caseless;
+    rc.options = caseless ? NGX_REGEX_CASELESS : 0;
 #endif
 
     clcf->regex = ngx_http_regex_compile(cf, &rc);