Reactor: Fix Frac generic code generation
Reactor: Fix Frac generic code generation

This commit fixes `Frac(Float)` and `Frac(Float4)` generic LLVM code
generation.

See also: https://bugs.chromium.org/p/swiftshader/issues/detail?id=74

Bug: b/115344057
Test: functional.shaders.builtin_functions.precision.fract.highp_vertex
Test: functional.shaders.builtin_functions.precision.fract.highp_fragment
Change-Id: I027b7ab44ba3060dc100a220ba19e5275f41d4c9
Reviewed-on: https://swiftshader-review.googlesource.com/20933
Reviewed-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>
Reviewed-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>
Tested-by: Chris Forbes <c3279c50043e18e9442c1ae071cafa0e7a4ca967@google.com>

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