Broken behavior when using the system copy of libyajl

[darix]

1. libyajl2 gem allows to use the system copy instead of compiling the intree copy
2. many linux distributions split the library packages in 2 parts
   • one that holds the actual shared library (libyajl.so.*)
   • one that holds the devel files (libyajl.so and the headers)
3. the code in lib/ffi_yajl/ext.rb seems to be weird
   • it seems FFI.map_library_name("yajl") always returns the unversioned file name. even if that isnt present. to fix the actual loading i had to install the devel package.
   • you concat that with the lib path to the libyajl2 intree copy (which doesnt exist on my system)
   • i double checked this with @headius and @whitequark and they both think there is a lot of unneeded code there.
   • the code wouldnt work on jruby
4. what was wrong with the existing libyajl bindings? it cant be jruby support...

At the very least ffi-yajl should try to load the versioned library name instead of the unversioned one.

[darix]

for the record: this was on MRI 2.1.4 + FFI 1.9.6

[lamont-granquist]

The way that -dev and -devel packages are built they should only have *.h header files in them. They shouldn't be touching the lib directory and the base non-dev[el] packages should contain both the versioned library and its symlinks. So I can't understand what the root cause of this bug is. I also can't replicate it on Ubuntu or Mac or CentOS. Using the environment variable to build against the system yajl got an overhaul in #52 so this may have fixed some issue. The solution of including searching the versioned filenames, though, is not necessary.