Standard C99 defines '_Bool' type.
But '_Bool' is not listed on 'Table 6.1' of opencl-1.0.43.pdf.
Instead, 'bool' type is listed on Table 6.1.
According to description of 'bool' at Table6.1,
behavior of standard C99's '_Bool' and OpenCL's 'bool' are same.
Why does OpenCL define the 'bool' type?