Remove filename extension crap for OS compatibility

The only variable that is used is HOST_LOADLIBES, defined for the
cygwin case in the kconfig build. Since we don't support cygwin,
simply get rid of this.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>