subversion16: don't try to use httpd

Fixes #373.
postgresql 8.4.21
postgresql 9.0.17
postgresql 9.1.13
postgresql 9.2.8
llvm: use install_symlink to link executables and manpages
spidermonkey: use block-form of mkdir
guile: use install_symlink
gcc: disable multilib on 32-bit hosts

Fixes #378.
Fixes #382.
Address URL audits
subversion17: always use Homebrew openssl