[gdb/testsuite] Fix FAIL in gdb.mi/mi-var-child-f.exp

[gdb/testsuite] Fix FAIL in gdb.mi/mi-var-child-f.exp

When running test-case gdb.mi/mi-var-child-f.exp on openSUSE Tumbleweed
(with glibc 2.34) I run into:
...
(gdb) ^M
PASS: gdb.mi/mi-var-child-f.exp: mi runto prog_array
Expecting: ^(-var-create array \* array[^M
]+)?(\^done,name="array",numchild="[0-9]+",value=".*",type=.*,has_more="0"[^M
]+[(]gdb[)] ^M
[ ]*)
-var-create array * array^M
&"Attempt to use a type name as an expression.\n"^M
^error,msg="-var-create: unable to create variable object"^M
(gdb) ^M
FAIL: gdb.mi/mi-var-child-f.exp: create local variable array (unexpected output)
...

The problem is that the name array is used both:
- as the name for a local variable
- as the name of a type in glibc, in file malloc/dynarray-skeleton.c, as included
  by nss/nss_files/files-hosts.c.

Fix this by ignoring the shared lib symbols.

Likewise in a couple of other fortran tests.

Tested on x86_64-linux.