Add several missing dependencies to the port.

`make stage-qa' was complaining about a lot of missing dependencies:

• Amarok actually links against MySQL, so we need USES=mysql, not USES=mysql:embedded.
• Add USE_KDE=soprano and USE_GL=gl.
• Add several missing X11 dependencies that were being pulled indirectly.
• The IPOD option causes the iPod plugin to link against a few other libraries via libgpod-1.0.pc, so add them.
• The MP3TUNES option needs either libgcrypt or OpenSSL; explicitly disable libgcrypt and add USES=ssl as required.
• Fix a capitalization typo in MP3TUNES_CMAKE_OFF that was preventing the MP3Tunes code from being properly disabled in CMake.

Based on an initial patch sent by Matthey Rezny <matthew@reztek.cz>.

PR: 214184
MFH: 2016Q4