prepare-cross-toolchain: Copy all runtime DLLs to the main bin directory

We used to copy libc++ and libunwind, since those were needed
to actually run the toolchain - but others, like the asan runtime,
may be needed for the user to be able to run the executables that
are built. If this bin directory is in the user's $PATH, they should
be picked up automatically.

For distribution, and for architectures other than the default,
the user still needs to use the binaries from the arch specific
directories.

prepare-cross-toolchain.sh

@@ -30,12 +30,11 @@ CLANG_RESOURCE_DIR="$("$SRC/bin/clang" --print-resource-dir)"
 CLANG_VERSION=$(basename "$CLANG_RESOURCE_DIR")
 
 # If linked to a shared libc++/libunwind, we need to bundle those DLLs
-# in the bin directory.
-for i in libc++ libunwind; do
-    if [ -f $SRC/$CROSS_ARCH-w64-mingw32/bin/$i.dll ]; then
-        cp $SRC/$CROSS_ARCH-w64-mingw32/bin/$i.dll $DEST/bin
-    fi
-done
+# in the bin directory. For simplicity, copy all runtime DLLs to the
+# bin directory - that way, users who have this directory in $PATH
+# can run the executables they've built directly without fiddling
+# with copying them.
+cp $SRC/$CROSS_ARCH-w64-mingw32/bin/*.dll $DEST/bin
 
 # Copy the clang resource files (include, lib, share). The clang cross
 # build installs the main headers, but since we didn't build the runtimes