Configure: fixed Linux crypt_r() test to add libcrypt.

Previously, the resulting binary was successfully linked
because libcrypt was added in a separate test for crypt().

Patch by Piotr Sikora.

auto/os/linux

@@ -228,6 +228,10 @@ ngx_feature_test="struct crypt_data  cd;
                   crypt_r(\"key\", \"salt\", &cd);"
 . auto/feature
 
+if [ $ngx_found = yes ]; then
+    CRYPT_LIB="-lcrypt"
+fi
+
 
 ngx_include="sys/vfs.h";     . auto/include