fixes typo in webclcontext.h; reviewed by Antonio
2013-03-19  Arnaud Renevier  <a.renevier@sisa.samsung.com>

Reviewed by Antonio: prevents data corruption for kernel sources and options
        Issue #179

        get CString and underlying char* data in two separate instructions.

        * platform/opencl/ComputeContextCL.cpp:
        (WebCore::ComputeContext::createProgram):
        (WebCore::ComputeContext::buildProgram):