Fixes for mac

Sample output on MacBook Pro Retina, 15-inch, Late 2013:

	Platform: Apple
	  Device: Iris Pro
	    Driver version  : 1.2(May  5 2014 20:39:23) (Macintosh)
	    Compute units   : 280
	    Clock frequency : 1200 MHz

	    Global memory bandwidth (GBPS)
	      float   : 33.06
	      float2  : 21.28
	      float4  : 24.55
	      float8  : 21.64
	      float16 : 7.24

	    Single-precision compute (GFLOPS)
	      float   : 536.79
	      float2  : 693.48
	      float4  : 688.65
	      float8  : 725.56
	      float16 : 699.76

	    No double precision support! Skipped

	    Transfer bandwidth (GBPS)
	      enqueueWriteBuffer         : 5.11
	      enqueueReadBuffer          : 4.33
	      enqueueMapBuffer(for read) : 257.15
	        memcpy from mapped ptr   : 4.70
	      enqueueUnmap(after write)  : 6900.65
	        memcpy to mapped ptr     : 5.27

	    Kernel launch latency : 50.36 us

	  Device: Intel(R) Core(TM) i7-4750HQ CPU @ 2.00GHz
	    Driver version  : 1.1 (Macintosh)
	    Compute units   : 8
	    Clock frequency : 2000 MHz

	    Global memory bandwidth (GBPS)
	      float   : clEnqueueNDRangeKernel(-54)
	      Tests skipped

	    Single-precision compute (GFLOPS)
	      float   : clEnqueueNDRangeKernel(-54)
	      Tests skipped
	clCreateKernel(-46)
	      Tests skipped

	    Transfer bandwidth (GBPS)
	      enqueueWriteBuffer         : 6.13
	      enqueueReadBuffer          : 6.06
	      enqueueMapBuffer(for read) : 35791.39
	        memcpy from mapped ptr   : 6.17
	      enqueueUnmap(after write)  : 8918.12
	        memcpy to mapped ptr     : 6.14

	    Kernel launch latency : clEnqueueNDRangeKernel(-54)
	    Tests skipped