Fix the output names of libraries in Windows.

 * Set shared lib to zlib1.dll
 * Set implib to libz.dll.a in MinGW
 * Set static lib to libz.a in MinGW
Fix incorrect indent in CMakeLists.txt
Simplify installation paths.
Refine zlib1.rc compilation.
Fix MingGW i686 build error with asm implemenation.