host-gcc-final: don't install a potentially dead symlink

gcc used to be installed into $(HOST_DIR)/usr/$(GNU_TARGET_NAME) but
since gcc 4.9 this is no longer the case.  Therefore, the cc -> gcc
symlink that is created in that we create in that directory is dead.

There don't seem to have been any problems due to the missing gcc and
cc in $(HOST_DIR)/usr/$(GNU_TARGET_NAME), things seems to build fine
without it. The cc -> gcc symlinks in general should not be needed
anyway, since we always pass the appropriate CC variable to the
package build system.

Therefore, let's remove the cc -> gcc symlink in
$(HOST_DIR)/usr/$(GNU_TARGET_NAME) - also for pre-4.9 gcc versions.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>