- The default is actually "html" not "all", so fix comment to match
reality.
- A shell script is run in a sub-shell, and the parent's current
directory won't be affected, so it's pointless (and confusing) to
try to restore it at the end of the script.
- Remove trailing ";" from "export FOO=bar;" - it's not required,
though is valid (it means every "export" is followed by an empty
statement).
- After adjusting doxygen.log, simply use "mv" to replace the
original, rather than "cat" then "rm".
Fixes#17001
aa4811cdbb
