TravisCI broken for "conky-all" but not "conky"

[npyl]

There are some problems, like building the toluapp target and installing cairo-xlib with homebrew.

[npyl]

Problems right now:

• (1) build toluapp (checked because it has been amended by installing pre-compiled binaries in the right place before build process needs them.)
• (2) cairo-conky target doesn't use cairo-xlib thus it fails because cairo is not compiled with xlib support enabled.
• (3) conky or maybe cairo-imlib2-helper (?) fails to link because there are some undefined references related to imlib2 and cairo. (I haven't figured out how yet.)

[npyl]

For (2), although we include cairo-xlib in PKG_CONFIG_PATH, it doesn't seem like xcode is able to locate it.

Force-linking cairo-xlib with homebrew fixes the problem but we shouldn't rely on this solution because on a user's mac it could break cairo.

[npyl]

For now I am thinking we should finish with (2) and then go to (3).
Lets also try a TravisCI build with (2) only.

[npyl]

Without (2) and (3) TravisCI worked nicely. (after a mind-numbingly long time.)
This could be used as a ground to work on (2) and finally (3).

[npyl]

More troubleshooting:

A notable question would be:

• Can I enable just LUA_CAIRO without LUA_IMLIB2 and everything build fine? (case senario 1)

If this works, can I do the opposite:

• Enable LUA_IMLIB2 without LUA_CAIRO and everything build fine? (case senario 2)

[npyl]

Case senario (1) worked as can be observed in f63bf46 . (I've even taken a stab at enabling LUA_RSVG and it worked.)

Now for case senario (2).

[npyl]

Case senario 2 failed.
That is were we should focus our debugging.

[npyl]

Why is this happening?

[npyl]

Based on this we need to ship a version of imlib2 with xlib support enabled.

[npyl]

The cairo-xlib (falsely called conky-all) branch has been merged to master.
Cairo-xlib problem was unrelated to imlib2 problem.

[npyl]

This can be solved if we explicitly add /usr/local/opt/imlib2-xlib/lib/libImlib2.dylib in conky's linker flags. But why is this required? It shouldn't be...