add deps/build.jl

 - inspired by Gurobi.jl
 - seems to work when `/usr/lib/libscip.so` exists.

REQUIRE

@@ -1 +1,2 @@
 julia 1.0
+Compat

deps/build.jl

@@ -1 +1,38 @@
+using Compat
 using Libdl
+
+depsfile = joinpath(dirname(@__FILE__), "deps.jl")
+if isfile(depsfile)
+ rm(depsfile)
+end
+
+function write_depsfile(path)
+ f = open(depsfile, "w")
+ println(f, "const libscip = \"$path\"")
+ close(f)
+end
+
+libname = "libscip.so"
+paths_to_try = [libname]
+
+if haskey(ENV, "SCIPOPTDIR")
+ if Compat.Sys.isunix()
+ push!(paths_to_try, joinpath(ENV["SCIPOPTDIR"], "lib", libname))
+ end
+end
+
+found = false
+for l in paths_to_try
+ d = Libdl.dlopen_e(l)
+ if d != C_NULL
+ global found = true
+ write_depsfile(l)
+ break
+ end
+end
+
+if !found && !haskey(ENV, "SCIP_JL_SKIP_LIB_CHECK")
+ error("Unable to locate SCIP installation. " *
+ "Note that this must be downloaded separately from scip.zib.de. " *
+ "Please set the environment variable SCIPOPTDIR to SCIP's installation path.")
+end