Fix curl CMake build.

This commit fixes the cmake build of curl, and cleans up the
cmake code a little.  It removes some commented out code and
some trailing whitespace.  To get curl to build the binary
tree include/curl directory needed to be added to the include
path. Also, SIZEOF_SHORT needed to be added.  A check for the
lack of defines of SIZEOF_* for warnless.c was added.