Importing log2f fix for JB-MR1
Importing log2f fix for JB-MR1

Bug 28474248

Change-Id: Id5b93f3494c918cb344e5da7010dfa48a25cdde1
Reviewed-on: https://swiftshader-review.googlesource.com/5263
Tested-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Reviewed-by: Nicolas Capens <0612353e1fcebbfd4b302d9337447ca0cdfa9122@google.com>

bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,google/swiftshader,bkaradzic/SwiftShader,bkaradzic/SwiftShader,google/swiftshader,bkaradzic/SwiftShader