Bug#864036: stretch: mention that the -fPIC error message is misleading

[Adrian Bunk <bunk@debian.org>]

Package: release-notes
Severity: minor

5.1.6.1. Behaviour changes of PIE for system administrators and developers
...
  Static libraries being compiled into an executable now also need to be compiled as position independent code. The following error message from the linker is a symptom of this:
    relocation ... against '[SYMBOL]' can not be used when making a shared object; recompile with -fPIC


Please add a sentence like:

Note that even though the error message says -fPIC, it is sufficient to
recompile with -fPIE (which is the default in the GCC 6 packages that are
part of stretch).