Enable hardcoded tables for ia64 shared builds.

At least for cross-compilation with Gentoo gcc 4.4.2 it fixes the build errors
due to GPREL 22 being insufficient for the .bss size of > 4 MB without it.
Why these errors do not appear with static builds is unclear, it is not due
to PIC (shared builds with PIC disabled show the same issue).

Originally committed as revision 20409 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1800,6 +1800,8 @@ case "$arch" in
         arch="ia64"
         enable fast_64bit
         spic=$shared
+        # HACK: currently fails to build if .bss is > 4MB and shared libs are built
+        enabled shared && enable hardcoded_tables
     ;;
     m68k)
         arch="m68k"