Run gdb.base/sizeof.exp with board having gdb,noinferiorio

Run gdb.base/sizeof.exp with board having gdb,noinferiorio

In my remote cross testing (x86_64 host and aarch64 target), the test
gdb.base/sizeof.exp is skipped because gdb,noinferiorio is defined in
my gdbserver board file.  Tests are skipped because the test checks
the expected value from the program's output, but I don't see why must
do it this way.  With my patch applied, we can save the result in variable
in the program, and check the variable then.  Then, the test doesn't rely
on inferiorio.

gdb/testsuite:

2015-12-03  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/sizeof.c: Don't include stdio.h and
	../lib/unbuffer_output.c.
	(main): New variable 'size' and 'value'.  Remove printf and
	gdb_unbuffer_output.  Assign return value to size and value.
	* gdb.base/sizeof.exp: Remove the checking to gdb,noinferiorio
	at the beginning.
	(check_sizeof): Check the result by printing variable 'size'.
	(check_valueof): Check the result by printing variable 'value'.