package/bullet: needs wchar

package/bullet: needs wchar

bullet needs wchar since bump to version 3.09 in commit
28b4947ed8f53c4edfbf8fef9304dc76480c01ca:

/home/giuliobenetti/autobuild/run/instance-0/output-1/build/bullet-3.09/examples/ThirdPartyLibs/Gwen/Structures.h:42:14: error: 'wstring' in namespace 'std' does not name a type
   42 | typedef std::wstring UnicodeString;
      |              ^~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/2b1158970fc45e9ebd4be4d726352166ed417a1f

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