package/libloki: fix build with gcc 11

package/libloki: fix build with gcc 11

Fix the following build failure with gcc 11:

In file included from ../include/loki/SmartPtr.h:33,
                 from SmartPtr.cpp:20:
../include/loki/SmallObj.h: At global scope:
../include/loki/SmallObj.h:462:57: error: ISO C++17 does not allow dynamic exception specifications
  462 |         static void * operator new ( std::size_t size ) throw ( std::bad_alloc )
      |

Fixes:
 - http://autobuild.buildroot.org/results/768727160beaca5df3ef18be29cfbaa3ced67ad5

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>