game3d_example needs -lpthread to compile

[Merrill Roller]

Reported by a USB-2 user:

On fedora 15/gcc4.6.3, needed to change the Makefile in src/ to:

game3d_example_LDADD = -lm -lpthread

I think -lpthread is needed apparently, from this output:

/usr/bin/ld: game3d_example.o: undefined reference to symbol 'pthread_create@@GLIBC_2.1'
/usr/bin/ld: note: 'pthread_create@@GLIBC_2.1' is defined in DSO /lib/libpthread.so.0 so try adding it to the linker command line
/lib/libpthread.so.0: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make: *** [game3d_example] Error 1