- fixed semantics of host atomics to match (fetch & add) device ones - used real atomics under GCC
- fixed semantics of host atomics to match (fetch & add) device ones
- used real atomics under GCC

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 18823652]

kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,NVlabs/nvbio,kimrutherford/nvbio,NVlabs/nvbio