diff --git a/vendor/libpng b/vendor/libpng
new file mode 160000
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+++ b/vendor/libpng
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+Subproject commit a37d4836519517bdce6cb9d956092321eca3e73b
diff --git a/vendor/zlib b/vendor/zlib
new file mode 160000
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--- /dev/null
+++ b/vendor/zlib
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+Subproject commit 21767c654d31d2dccdde4330529775c6c5fd5389