mass rewrite of find parameters to cross-platform style

Fixes #9044, close #9667. Thanks to @taku0 for suggesting this solution.
Now we have no modes starting with `/` or `+`.

Rewrite the `-perm` parameters of find:
 - completely safe: rewrite `/0100` and `+100` to `-0100`,
 - slightly semantics-changing: rewrite `+111` to `-0100`.
I cross-verified the `find` manual pages for Linux, Darwin, FreeBSD.

pkgs/development/tools/misc/patchelf/setup-hook.sh

@@ -9,7 +9,7 @@ patchELF() {
     if [ -e "$prefix" ]; then
         find "$prefix" \( \
             \( -type f -a -name "*.so*" \) -o \
-            \( -type f -a -perm /0100 \) \
+            \( -type f -a -perm -0100 \) \
             \) -print -exec patchelf --shrink-rpath '{}' \;
     fi
     stopNest