CRssManager: add locking to protect maps
CSettings/CRssManager: no need to call Clear() in destructor

Calling Clear() in CSettings destructor results in a call to
CRssManager::Clear() but depending on the destruction order of static variables
the CRssManager instance may have already been destroyed which can result in
an access violation exception.
Fix libffi link warnings 'ARM function not 4-byte aligned' when build for ios.
Merge pull request #2441 from ulion/fix_libffi_function_align_link_warning_on_ios

Fix libffi link warnings 'ARM function not 4-byte aligned' when build for iOS
depends: grr, revert accidental commit that breaks android build
Merge pull request #2420 from Montellese/rssmanager_locks

fix possible access violation in CRssManager::Clear() during shutdown