vp78: Align the intra4x4_pred_mode_top array within VP8Macroblock

This array is written using AV_WN32A, assuming alignment.

This hopefully fixes the failing vp7 fate test on sparc.

Signed-off-by: Martin Storsjö <martin@martin.st>
disable -rpath-link on Solaris

The Solaris -rpath linker option parser is greedy.
build: add Solaris symbol versioning

The Solaris linker does not support globs in linker scripts for
symbol versioning (this is a GNU extension). Let's instead borrow
make_sunver.pl from GCC to make a description file that works
with the Solaris linker.