Every policy's documentation has a paragraph on what version of CMake
introduced it, how to set the policy, and whether CMake warns if the
policy is not set. The wording of this paragraph has diverged across
policies over time. Factor the paragraph out into a standard advice
document included by every policy.
In commit c4b4d8b3a6 (POSITION_INDEPENDENT_CODE: Manage link flags for
executables, 2018-10-02, v3.14.0-rc1~395^2) we accidentally removed our
Android-specific logic for PIE under the CMP0083 OLD behavior. Restore
it and also implement Android-specific logic for CMP0083 NEW behavior.
Fixes: #19393