Use native CUTEst and gcc if installed

[abelsiqueira]

Improve deps/build.jl to reuse CUTEst and gcc if they are already installed.
See MUMPS.jl for example.

[dpo]

I wonder why this simple build script

using BinDeps
@BinDeps.setup
libcutest = library_dependency("libcutest", aliases=["libcutest_double"])
@BinDeps.install Dict(:libcutest => :libcutest)

fails to detect libcutest, which is in /usr/local/lib when installed with Homebrew... Would you mind trying it at your end? You can test with

julia> using BinDeps
julia> BinDeps.debug("CUTEst")

[dpo]

Closed by #85.