Fixed race condition in server

src/activations.c

src/axpy.c

src/cnn.c

src/col2im.c

src/convolutional_layer.c

src/cost_layer.c

src/gemm.c

src/im2col.c

src/maxpool_layer.c

src/opencl.c

src/opencl.h

src/server.c

src/softmax_layer.c