glx: Can't mix declarations and code in X.org sources [CVE-2014-8098 pt. 9]

We're using compiler compatibility settings which generate warnings
when a variable is declared after the first statement.

Signed-off-by: Keith Packard <keithp@keithp.com>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>