emulators/vba: unbreak with libc++ 3.9

../GBA.cpp:1133:12: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../GBA.cpp:1148:12: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../GBA.cpp:1172:12: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../GBA.cpp:1192:12: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../Util.cpp:481:12: error: cannot initialize a variable of type 'char *' with an rvalue of type

  'const char *'
char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../Util.cpp:505:12: error: cannot initialize a variable of type 'char *' with an rvalue of type

  'const char *'
char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../Util.cpp:525:12: error: cannot initialize a variable of type 'char *' with an rvalue of type

  'const char *'
char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

../Util.cpp:555:12: error: cannot initialize a variable of type 'char *' with an rvalue of type

  'const char *'
char * p = strrchr(file,'.');
       ^   ~~~~~~~~~~~~~~~~~

In file included from expr.y:12:
In file included from ../../src/System.h:24:
In file included from ../../src/unzip.h:68:
In file included from /usr/include/zlib.h:34:
In file included from /usr/include/zconf.h:247:
/usr/include/c++/v1/stddef.h:52:7: error: reference to 'std' is ambiguous
using std::nullptr_t;

^

/usr/include/c++/v1/__nullptr:22:1: note: candidate found by name lookup is 'std'
_LIBCPP_BEGIN_NAMESPACE_STD
^
/usr/include/c++/v1/__config:388:47: note: expanded from macro '_LIBCPP_BEGIN_NAMESPACE_STD'
#define _LIBCPP_BEGIN_NAMESPACE_STD namespace std {inline namespace _LIBCPP_NAMESPACE {

^

/usr/include/c++/v1/__config:392:11: note: candidate found by name lookup is 'std::std'
namespace std {

^

Reported by: pkg-fallout