Don't install *.mountpoint targets

The *.mountpoint targets that installs /bionic/lib/lib*.so and
/bionic/bin/linker* are no longer needed.

Now, /system/lib/lib*.so and /system/bin/linker* are simply symlinks to
the corresponding files in the runtime apex. For example,

/system/lib/libc.so -> /apex/com.android.runtime/lib/bionic/libc.so

This is made possible because we now activate APEXes even before the
data partition is mounted. Before the data partition mounting, the
APEXes from the system partition are ativated. After the data partition
is mounted, updated APEXes in the partition (if any) are activated. As a
result, the symlink always points to the valid path regardless of
whether /data is mounted or not.

Bug: 125549215
Test: device boots
Change-Id: Ie7d83686abe00b3c436f9f9db75d4244200a0fc9