CPackIFW: Search algorithm update

Variables like CPACK_IFW_*_EXECUTABLE_FOUND now not needed
Fix a few more places to use cmsys::[io]fstream instead of std::fstream.
CPackIFW: Added support for multiple repositories

Now user can add IFW specific repo with cpack_ifw_add_repository macro
FindBoost: Avoid if() quoted auto-dereference

When testing CMAKE_CXX_COMPILER[_ID] values with if(MATCHES) or
if(STREQUAL), do not explicitly dereference or quote the variable.
We want if() to auto-dereference the variable and not its value.
Ninja: Fix variable duplication in RSP rules

Stream clear() resets stream state but does not actually clear its content.
Merge topic 'encoding-fstream'

42e39bb3 Fix a few more places to use cmsys::[io]fstream instead of std::fstream.
Merge topic 'cpack-ifw-updates'

ed9684a2 CPackIFW: Added support for multiple repositories
f9f74874 CPackIFW: Search algorithm update
Merge topic 'FindBoost-CMP0054'

c9300464 FindBoost: Avoid if() quoted auto-dereference
Merge topic 'fix-ninja-rsp-var-duplication'

71da30ca Ninja: Fix variable duplication in RSP rules