[runtimes] Modernize installation targets (#171677)

This patch moves away from using cmake_install scripts to install the
various targets when building runtimes, since those have been deprecated
by CMake. Instead, we use `cmake --install` which is the prefered
method.

This patch also localizes how we set dependencies on the various
installation targets, allowing the removal of a few global variables
that were used as lists.

Finally, it makes the way we set up installation targets for libc++,
libc++abi and libunwind consistent again.

NOKEYCHECK=True
GitOrigin-RevId: a9fadb3ed4fba28d031a4bc72de8f3fc15c08072

• include/CMakeLists.txt[diff]
• src/CMakeLists.txt[diff]