stdenv: fix self.cc check

Since ENV.cc/cxx are accessors to ENV, any values being passed through
are coerced into strings, which means that a nil `ENV.cc` is actually
an empty string - which isn't considered to be false in Ruby.

Fixes mistydemeo/tigerbrew#161.
Fixes mistydemeo/tigerbrew#135.
default_cc: locate already returns Pathnames
default_compiler: recognize gcc-4.0
stdenv: set correct compiler symbol for gcc 4.0
mitmproxy: switch to pillow; fixes #25522
minizip: needs newer autotools

Fixes mistydemeo/tigerbrew#164.
tor: needs newer openssl on < Snow Leopard

Fixes mistydemeo/tigerbrew#163.
tor: fix conditionals
Revert "stdenv: set correct compiler symbol for gcc 4.0"

This reverts commit f4dc5614953b3b90acc28c83262d56587b0616b1.
Revert "default_compiler: recognize gcc-4.0"

This reverts commit bedcbb806bb8a991a1317b4ccde8d16b6974cc46.
Revert "default_cc: locate already returns Pathnames"

This reverts commit 8ec6123d439e8f4d3586bbca6a426b726bd5e9dd.
Revert "stdenv: fix self.cc check"

This reverts commit 0e1d52c0d3945ae0ac69383c7734e425b7fbf8f1.
Recommit ENV changes
ENV.gcc: remove raise

This raise happened in no other ENV methods, and isn't really necessary
since fails_with guards against this method actually being called unless
gcc-4.2 is actually installed.
byobu 5.69

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
stdenv tests: add gcc-4.0 test
passenger: remove wrapper scripts because they cause problems.

Instead, create a locations.ini so that Passenger can always find its own libraries.
passenger: remove curl dependency.

Although Passenger needs libcurl, libcurl is already installed by
default on OS X. Passenger does not need any particular version of
libcurl, so there's no need to depend on the Homebrew curl. Depending
on the Homebrew curl is useless anyway because its header and library
files are not in the compiler's default search paths.