OGL: Correctly guard against array bounds of s_encodingPrograms

s_encodingPrograms is defined as an array with a length of 64. NUM_ENCODING_PROGRAMS is also defined as 64.

However 64 is out of bounds (0 - 63 only), so we want to be comparing for "equal to or greater than here"
Even if "64" will never happen as a value, it should still be validated against.