The script checks if -DCMAKE_BUILD_TYPE is passed in command line and if
it is not passed, passes -DCMAKE_BUILD_TYPE=Release. So now other build
types are supported, just pass -DCMAKE_BUILD_TYPE=<desired-type> to the
script $(TARGET)-cmake.
Fix https://github.com/mxe/mxe/issues/1697
- move cmake configuration from mxe-conf to cmake-conf
- replace `echo` with templates for readability and maintenance
- allow packages to set other dep files
- set CMAKE_POLICY_DEFAULT_CMPNNNN in wrapper since
`cmake_minimum_required` or `cmake_policy` can't be set in
toolchain (closes#971)