[ob/testsuite/mi] add #include lines for gcc HEAD

[Michael Chastain]

Committed.

===

2004-08-25  Michael Chastain  <mec.gnu@mindspring.com>

	* gdb.mi/basics.c: Include <stdio.h>.
	* gdb.mi/pthreads.c: Include <stdlib.h>.
	* gdb.mi/var-cmd.c: Include <stdlib.h>.