cmake.mk,rules.mk: fix host builds using CMake and ccache

Commit f98878e4 ("cmake.mk: set C/CXX compiler for host builds as
well") has introduced regression as it didn't taken usage of ccache into
the account so fix it by handling ccache use cases as well.

In order to get this working we need to export HOSTCXX_NOCACHE in
rules.mk as well.

Fixes: f98878e4 ("cmake.mk: set C/CXX compiler for host builds as well")
Reported-by: Ansuel Smith <ansuelsmth@gmail.com>
Tested-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: Petr Štetiar <ynezz@true.cz>
(cherry picked from commit 524fb564)