[PING, PATCH] fortran: fix -MT/-MQ adding additional target [PR47485]

[Jerry D]

Committed as:

commit e41a5a2a0832509fa1c0b7cab0c8001fadbd23d4 (HEAD -> master, 
origin/master, origin/HEAD)
Author: Jerry DeLisle <jvdelisle@gcc.gnu.org>
Date:   Tue Feb 4 17:21:42 2025 -0800

     Fortran: Fix PR 47485.

     The -MT and -MQ options should replace the default target in the
     generated dependency file. deps_add_target needs to be called before
     cpp_read_main_file, otherwise the original object name is added.

     Contributed by Vincent Vanlaer <vincenttc@volkihar.be>

             PR fortran/47485

     gcc/fortran/ChangeLog:

             * cpp.cc: fix -MT/-MQ adding additional target instead of
             replacing the default.

     gcc/testsuite/ChangeLog:

             * gfortran.dg/dependency_generation_1.f90: New test.

     Signed-off-by: Vincent Vanlaer <vincenttc@volkihar.be>