Fix quoting in libomp.a dune rule

Escape double quotes in the bash action to fix "Too many arguments for bash"
dune parsing error.

Author: taoeffect

src/quickjs/dune

@@ -64,8 +64,8 @@
     \"
     for p in $PAWTHS; do
       for matched_path in $p; do
-        if [ -f "$matched_path" ]; then
-          cp "$matched_path" "$OUT"
+        if [ -f \"$matched_path\" ]; then
+          cp \"$matched_path\" \"$OUT\"
           exit 0
         fi
       done