fix count(::BitArray; dims) (#39149)

Not sure why this worked before #37461, perhaps #9498?

Author: simeonschaub

base/bitarray.jl

@@ -1394,7 +1394,7 @@ function bitcount(Bc::Vector{UInt64}; init::T=0) where {T}
     return n
 end
 
-count(B::BitArray; init=0) = bitcount(B.chunks; init)
+_count(::typeof(identity), B::BitArray, ::Colon, init) = bitcount(B.chunks; init)
 
 function unsafe_bitfindnext(Bc::Vector{UInt64}, start::Int)
     chunk_start = _div64(start-1)+1

test/bitarray.jl

@@ -1221,6 +1221,7 @@ timesofar("datamove")
     end
 
     @test count(trues(2, 2), init=0x03) === 0x07
+    @test count(trues(2, 2, 2), dims=2) == fill(2, 2, 1, 2)
 end
 
 timesofar("find")