src/meta-openembedded:directfb: Fix C++17 build warning

DirectFB explicitly supports usage of C++. With C++17 and later the below
warning is given:

lib/direct/util.h:223:19:
warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
  223 |      register int ret = 0;
      |                   ^~~

To address that, this commit brings in the patch proposed by PR which
removes the usage of the register keyword:

deniskropp/DirectFB#25

Signed-off-by: Ricardo Simoes <ricardo.simoespt.bosch.com>
Signed-off-by: Mark Jonas <mark.jonasde.bosch.com>
Signed-off-by: Khem Raj <raj.khemgmail.com>