bwm-ng: fix building with clang.

* Use c89 inline rules so that clang can build it.

Closes #23676.
subversion: fix perl bindings.

* Add swig as dependency for bindings.
* Regenerate autotools as advice by upstream.
  - Depends on autotools for this purpose.
* Filter out "-isystem" flags from Makefiles after installing main
  components.
  - Homebrew uses "-isystem" in CPPFLAGS to help detecting system
    componenets, but subversion passes it to swig which doesn't
    understand this. Manually filtering them out make it compile.

Closes #20932.
Closes #22668.