gdb/testsuite: kfail some tests if using broken gcc

gdb/testsuite: kfail some tests if using broken gcc

In some cases the Fortran stride information generated by GCC is wrong
with versions of GCC after 7.x.x.  This commit adds kfails for the
tests in question with known bad versions of gcc.

The bug has been reported to GCC here:

  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92775

gdb/testsuite/ChangeLog:

	* gdb.fortran/derived-type-striding.exp: KFAIL if we are using a
	broken version of GCC.

Change-Id: Iaef08e5e2c87ab3d6983b88f749d40e01aea2bc6