multimedia/atomicparsley: unbreak with libc++ 3.9

AtomicParsley.cpp:1450:9: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char* orig_suffix = strrchr(originating_file, '.');
      ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

AtomicParsley.cpp:4467:10: error: assigning to 'char *' from incompatible type 'const char *'

suffix = strrchr(filePath, '.');
       ^ ~~~~~~~~~~~~~~~~~~~~~~

AtomicParsley.cpp:4483:9: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char* file_name = strrchr(filePath, '/');
      ^           ~~~~~~~~~~~~~~~~~~~~~~

AtomicParsley.cpp:5009:11: error: cannot initialize a variable of type 'char *' with an rvalue of type 'const char *'

char* suffix = strrchr(m4aFile, '.');
      ^        ~~~~~~~~~~~~~~~~~~~~~

PR: 212343
Reported by: antoine (via exp-run)