Ensure inference of Bool when array type is Any

[Tokazama]

While searching for invalidations with Static.jl I found that I was getting a handful on filter when the arrays eltype was Any. This fixed them.

[vtjnash]

This should already be implied?

julia> methods(ifelse)
# 1 method for generic function "ifelse":
[1] ifelse(condition::Bool, x, y) in Base at essentials.jl:556

[Tokazama]

That's not inferred internally though and causes invalidations. Here's the relevant ones I found that went away once I changed this. The number of invalidations here varies depending on the version but these are from master.

Starts at
 inserting ifelse(::False, x, y) in Static at /Users/zchristensen/.julia/packages/Static/KC67x/src/bool.jl:125 invalidated:
   mt_backedges: 1: signature Tuple{typeof(ifelse), Any, AbstractFloat, AbstractFloat} triggered MethodInstance for Base._fast(::typeof(max), ::AbstractFloat, ::AbstractFloat) (0 children)
                 2: signature Tuple{typeof(ifelse), Any, AbstractFloat, AbstractFloat} triggered MethodInstance for Base._fast(::typeof(min), ::AbstractFloat, ::AbstractFloat) (0 children)
                 3: signature Tuple{typeof(ifelse), Any, Int64, Int64} triggered MethodInstance for filter!(::Function, ::Vector{Union{Nothing, Base.UUID}}) (0 children)
                 4: signature Tuple{typeof(ifelse), Any, DateTime, Any} triggered MethodInstance for max(::DateTime, ::Any) (0 children)
                 5: signature Tuple{typeof(ifelse), Any, Int64, Int64} triggered MethodInstance for filter!(::Function, ::Vector{Base.UUID}) (0 children)
                 6: signature Tuple{typeof(ifelse), Any, Int64, Int64} triggered MethodInstance for filter!(::Function, ::Vector{Symbol}) (0 children)
                 7: signature Tuple{typeof(ifelse), Any, Int64, Int64} triggered MethodInstance for filter!(::Base.var"#40#42", ::Vector{Any}) (8 children)
   18 mt_cache
 inserting promote_rule(::Type{Bool}, ::Type{<:StaticBool}) in Static at /Users/zchristensen/.julia/packages/Static/KC67x/src/bool.jl:113 invalidated:
   backedges: 1: superseding promote_rule(::Type{Bool}, ::Type{T}) where T<:Number in Base at bool.jl:4 with MethodInstance for promote_rule(::Type{Bool}, ::Type{<:Integer}) (2 children)
   23 mt_cache

It also has a slight improvement on performance when it's hard to figure out what the return value of of f(::eltype(A)) is.

julia> v = Any[rand(Int, 1000)...];

julia> @btime filter(isodd, $(v));  # old
  10.828 μs (1 allocation: 7.94 KiB)

julia> @btime filter(isodd, $(v));  # new
  10.583 μs (1 allocation: 7.94 KiB)