Null terminate the CL source string.
Null terminate the CL source string.

Turns out that I wasn't actually terminating the source
string. This doesn't fix the compiler output, but it
doesn't hurt anything and makes it more likely for
me to be able to fix it in the future.

awatry/libvpx.opencl,awatry/libvpx.opencl,awatry/libvpx.opencl,awatry/libvpx.opencl