Installed SDFormat library missing dependencies

[stonier]

$ ldd /opt/drake/lib/libsdformat.so
linux-vdso.so.1 =>  (0x00007fff73158000)
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f136ba5d000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f136b754000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f136b53d000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f136b173000)
/lib64/ld-linux-x86-64.so.2 (0x000055e3e620d000)

Seems to be missing both libignition_math.so and libtinyxml.so.

These problems are turning up when trying to link the example in RobotLocomotion/drake-external-examples#22 -> undefined references to TiXml***. Since the example does not use these directly, they should be transitively picked up by a dependency on sdformat.

It looks like tinyxml is missed in sdformat-create-cps.py and both tinyxml and ignition math missed in the component dependencies. This does not explain why the installed libsdformat.so doesn't get linked against these libraries though.

[jamiesnape]

The linking issue is a long-standing Bazel problem. We can certainly update the CPS to ameliorate it, though.

[jamiesnape]

bazelbuild/bazel#492