`sinpi(::Rational{BigInt})` regression

[sostock]

#41744 broke sinpi(::Rational{BigInt}), which worked in v1.6, v1.8 and v1.9-beta:

Before:

julia> sinpi(big(1//1))
0.0

After #41744:

julia> sinpi(big(1//1))
ERROR: MethodError: no method matching sinpi_kernel(::BigFloat)
[...]

[sostock]

Other Rational types have problems with overflow:

Before:

julia> sinpi(typemax(Int64)//1)
0.0

After:

julia> sinpi(typemin(Int64)//1)
ERROR: OverflowError: 2 * -9223372036854775808 overflowed for type Int64
[...]