Put the GCC DLL replacement back

deps/build.jl

@@ -1,2 +1,61 @@
-using WinRPM
+using WinRPM, SHA, Compat
 WinRPM.update()
+
+# update julia's gcc dlls
+if is_windows()
+    winrpm_bin = joinpath(WinRPM.installdir, "usr", Sys.MACHINE,
+        "sys-root", "mingw", "bin")
+    dlls = ["libgfortran-4", "libquadmath-0", "libstdc++-6", "libwinpthread-1",
+        "libssp-0", Sys.WORD_SIZE==32 ? "libgcc_s_sjlj-1" : "libgcc_s_seh-1"]
+    dlls_to_download = Compat.String[]
+    for lib in dlls
+        if !isfile(joinpath(winrpm_bin, lib * ".dll"))
+            push!(dlls_to_download, replace(lib, "-", ""))
+        end
+        # try to clean up -copy remnants
+        if isfile(joinpath(JULIA_HOME, lib * "-copy.dll"))
+            try
+                rm(joinpath(JULIA_HOME, lib * "-copy.dll"))
+            end
+        end
+    end
+    if !isempty(dlls_to_download)
+        WinRPM.install(dlls_to_download; yes = true)
+    end
+    dlls_to_update = Compat.String[]
+    for lib in dlls
+        local sha_current, sha_new
+        if isfile(joinpath(JULIA_HOME, lib * ".dll"))
+            open(joinpath(JULIA_HOME, lib * ".dll")) do f
+                sha_current = sha256(f)
+            end
+        else
+            sha_current = UInt8[]
+        end
+        open(joinpath(winrpm_bin, lib * ".dll")) do f
+            sha_new = sha256(f)
+        end
+        if sha_current != sha_new
+            push!(dlls_to_update, lib)
+        end
+    end
+    if !isempty(dlls_to_update)
+        try
+            for lib in dlls_to_update
+                # it's possible to move an in-use dll and put a new file where
+                # it used to be, but not delete or overwrite it in-place?
+                if isfile(joinpath(JULIA_HOME, lib * ".dll"))
+                    mv(joinpath(JULIA_HOME, lib * ".dll"), joinpath(JULIA_HOME, lib * "-copy.dll"))
+                end
+                cp(joinpath(winrpm_bin, lib * ".dll"), joinpath(JULIA_HOME, lib * ".dll"))
+            end
+            warn("Updated Julia's gcc dlls, you may need to restart Julia for some WinRPM packages to work.")
+        catch err
+            buf = PipeBuffer()
+            showerror(buf, err)
+            warn("Could not update Julia's gcc dlls, some WinRPM packages may not work.\n" *
+                "Error was: $(readstring(buf))\n" *
+                "Try running Julia as administrator and calling `Pkg.build(\"WinRPM\")`.")
+        end
+    end
+end