[Bug fortran/39239] Reject SAVEd variables EQUIVALENCEd to a COMMON

[koenigni at student dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39239

--- Comment #6 from Nicolas Koenig <koenigni at student dot ethz.ch> ---
Created attachment 40962
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40962&action=edit
Proposed patch for EQUIVALENCE / VOLATILE

This patch should cover the case of one EQUIVALENCE object being VOLATILE (In
this case every object should be volatile according to the standard). It also
fixes a testcase (gfortran.dg/volatile11.90) related to this.