#189 char out of range compiling faac with c++11

[Dan Kegel]

Building faac with a c++11 compiler, e.g.
CXX="clang++ -std=c++11 -stdlib=libc++" ./configure
make

fails with lots of errors like

mp4atom.cpp:267:34: error: constant expression evaluates to 169 which cannot be narrowed to type 'char' [-Wc++11-narrowing]
static const char name[5]={0251,'n', 'a', 'm', '\0'};
^~~~
mp4atom.cpp:267:34: note: override this message by inserting an explicit cast

The attached patch lets it at least compile.