Changes

testenv: use separate install dir for --asan

The --asan flag builds all Osmocom components with address sanitizer
enabled. Use a separate install dir from the non-asan version to ensure
we don't end up with using non-asan versions. (A separate make dir is
already used.)

Bump make_dir_version to avoid having markers for already installed
binaries / libraries in the make dir, which are invalid now for
asan-builds as we switched the install dir.

Fixes: c3657172 ("testenv: add run --asan")
Change-Id: Ic75452b75d4c3ee8045b68353830b5532e1ce90e