As reported by Rainer Jung, Curl may not be mandatory to build
ModSecurity core. This patch make it optional by:
- Concentrate all downloads using curl on msc_remote_rules.c
- Split Curl build definitions checks into: WITH_CURL, WITH_REMOTE_RULES
and WITH_CRYPTO.
- WITH_CURL: Contains Culr headers and binaries during the build time.
- WITH_REMOTE_RULES: Currently enabled if Curl is present.
- WITH_CRYPTO: Set if apr tool was compiled with crypto support.
- Renames msc_remote_grab_content to msc_remote_download_content
On IIS CA validation was not working as libcurl on windows does not look for a
certificate store, unless it is specified. The resource downloads are now
respecting the SecRemoteRulesFailAction.
