Use gdb_test_no_output for compile tests expected to pass

Use gdb_test_no_output for compile tests expected to pass

There is a small think-o in compile.exp:

if { $srcfile3 != "" } {
    gdb_test "p constvar" " = 3"
    gdb_test "info addr constvar" {Symbol "constvar" is constant\.}

    gdb_test "compile code globalvar = constvar;"; # INCORRECT
    gdb_test "print globalvar" " = 3" "print constvar value"
} else {
    untested "print constvar value"
}

The line marked INCORRECT runs a simple "compile code" which is expected
to succeed.  When this happens, the compile plug-in and GDB will not
output anything.  The use of gdb_test matches against anything.

This is certainly not the intent, and this patch corrects the two instances
of this in the file.  [The rest of gdb.compile looks okay.]

testsuite/ChangeLog:

	* gdb.compile/compile.exp: Use gdb_test_no_output for "compile code"
	tests expected to pass.