Add clBuildProgram to command-buffer extension samples (#869)

The sample code in the `cl_khr_command_buffer` and
`cl_khr_command_buffer_mutable_dispatch` extensions was
missing a call to `clBuildProgram` which would be required
for the sample to work.

Author: Ewan Crawford

ext/cl_khr_command_buffer.asciidoc

@@ -1797,6 +1797,8 @@ Add to Table 37, _Event Command Types_:
         clCreateProgramWithSource(context, 1, &code, &length, &error);
     CL_CHECK(error);
 
+    CL_CHECK(clBuildProgram(program, 1, &device, nullptr, nullptr, nullptr));
+
     cl_kernel kernel = clCreateKernel(program, "vector_addition", &error);
     CL_CHECK(error);
 

ext/cl_khr_command_buffer_mutable_dispatch.asciidoc

@@ -40,6 +40,7 @@ Aharon Abramson, Intel. +
 Ben Ashbaugh, Intel. +
 Boaz Ouriel, Intel. +
 Pekka Jääskeläinen, Tampere University +
+Jan Solanti, Tampere University +
 Nikhil Joshi, NVIDIA +
 James Price, Google +
 
@@ -776,6 +777,8 @@ command-buffer submissions.
         clCreateProgramWithSource(context, 1, &code, &length, &error);
     CL_CHECK(error);
 
+    CL_CHECK(clBuildProgram(program, 1, &device, nullptr, nullptr, nullptr));
+
     cl_kernel kernel = clCreateKernel(program, "vector_addition", &error);
     CL_CHECK(error);