Add GC.at-preserve for some pointer calls, fix #529.

Author: fredrikekre

src/MArray.jl

@@ -113,21 +113,21 @@ end
 ####################
 
 @propagate_inbounds function getindex(v::MArray, i::Int)
-    @boundscheck checkbounds(v,i) 
+    @boundscheck checkbounds(v,i)
     T = eltype(v)
-    
+
     if isbitstype(T)
-        return unsafe_load(Base.unsafe_convert(Ptr{T}, pointer_from_objref(v)), i)
+        return GC.@preserve v unsafe_load(Base.unsafe_convert(Ptr{T}, pointer_from_objref(v)), i)
     end
     v.data[i]
 end
 
 @inline function setindex!(v::MArray, val, i::Int)
-    @boundscheck checkbounds(v,i) 
+    @boundscheck checkbounds(v,i)
     T = eltype(v)
 
     if isbitstype(T)
-        unsafe_store!(Base.unsafe_convert(Ptr{T}, pointer_from_objref(v)), convert(T, val), i)
+        GC.@preserve v unsafe_store!(Base.unsafe_convert(Ptr{T}, pointer_from_objref(v)), convert(T, val), i)
     else
         # This one is unsafe (#27)
         # unsafe_store!(Base.unsafe_convert(Ptr{Ptr{Nothing}}, pointer_from_objref(v.data)), pointer_from_objref(val), i)