fix cmake build on MSVC with option AMD64

A small C source file is needed to call the actual assembler function,
include it in the source list to fix a linker error complaining about
missing inflate_fast() function.
clean up indention and long lines
increase minimum cmake version to 2.8.11 and use new features

- installs zlib-config.cmake and related files to allow library users to
make use of imported targets.
- ues target_compile_definitions to pass compiler defines and correctly
propagate them to library users (ZLIB_DLL)
- use target_include_directories and generator expressions to propagate
include directories to library users
fixed: wrong directory to include zlib-targets.cmake from