[Ada] Arrange not to set DECL_ARTIFICIAL on elab procs

[Ada] Arrange not to set DECL_ARTIFICIAL on elab procs

Unlike, say, clones created internally by the compiler, elab procs
materialize specific user code and flagging them artificial now takes
elab code away from gcov's analysis, a regression compared to previous
releases.

On the testcase below:

package Gcov_Q is
   function F (X : Integer) return Integer is (X + 1);
end;

with Gcov_Q;
package Gcov_P is
   Y : Integer := Gcov_Q.F (X => 1);
end;

with Gcov_P;
procedure Gcov_Test is
begin
   if Gcov_P.Y /= 2 then
      raise Program_Error;
   end if;
end;

After compiling with:

  gnatmake -f -g gcov_test.adb \
    -cargs -ftest-coverage -fprofile-arcs \
    -largs -fprofile-generate

and executing with

  ./gcov_test

We expect

   gcov gcov_p

to produce a gcov_p.ads.gcov report.

2019-07-08  Olivier Hainque  <hainque@adacore.com>

gcc/ada/

	* gcc-interface/trans.c (Compilation_Unit_to_gnu): Don't request
	DECL_ARTIFICIAL_P on elab proc declarations.

From-SVN: r273207