treewide: rename bad filenames

Most of these can easily be moved to subdirectories of other
directories. This helps reduce clutter in the main trees.

pkgs/development/compilers/emscripten/fastcomp/default.nix

@@ -0,0 +1,28 @@
+{ newScope, stdenv, binutils, wrapCCWith, symlinkJoin }:
+let
+  callPackage = newScope (self // {inherit stdenv;});
+
+  self = {
+    emscriptenfastcomp-unwrapped = callPackage ./emscripten-fastcomp.nix {};
+    emscriptenfastcomp-wrapped = wrapCCWith {
+      cc = self.emscriptenfastcomp-unwrapped;
+      # Never want Apple's cctools for WASM target
+      bintools = binutils;
+      libc = stdenv.cc.libc;
+      extraBuildCommands = ''
+        # hardening flags break WASM support
+        cat > $out/nix-support/add-hardening.sh
+      '';
+    };
+    emscriptenfastcomp = symlinkJoin {
+      name = "emscriptenfastcomp";
+      paths = [ self.emscriptenfastcomp-wrapped self.emscriptenfastcomp-unwrapped ];
+      preferLocalBuild = false;
+      allowSubstitutes = true;
+      postBuild = ''
+        # replace unwrapped clang-3.9 binary by wrapper
+        ln -sf $out/bin/clang $out/bin/clang-[0-9]*
+      '';
+    };
+  };
+in self