Merging gdb-jit changes for arm support + enhancements into top-of-trunk....

Added gdb-jit interface support for ARM. Compressed .debug_line table by 1)
removing duplicate adjacent entries having the same line number, and 2) using
special opcodes to encode multiple machine register state changes in one byte.
Also made a fix involving the order in which static initializers are performed.

Patch by Shasank Chavan of Hewlett-Packard Development Company, LP 

BUG=none
TEST=Try building for arm

Committed: http://code.google.com/p/v8/source/detail?r=6801

[shasank.chavan, 2011-02-15 20:00:22]

Re-submitting changes to gdbjit support for + enhancements to debug line table
compression.

- Shasank