Subzero: Fix unittest build dependencies.

Subzero: Fix unittest build dependencies.

The unittest .o files also depend on some of the llvm2ice headers, as well as the unittest headers.

To reproduce the problem, try this:

make -f Makefile.standalone clean
make -f Makefile.standalone check-unit 2>/dev/null | grep BitcodeMunge.cpp

This will print a line containing BitcodeMunge.cpp.

Now do:

touch unittest/BitcodeMunge.h
make -f Makefile.standalone check-unit 2>/dev/null | grep BitcodeMunge.cpp

This should print a line, but it doesn't.

Finally:

touch src/PNaClTranslator.h
make -f Makefile.standalone check-unit 2>/dev/null | grep BitcodeMunge.cpp

This should also print a line, but it doesn't.

With this patch, the unittest files get rebuilt after header file changes.

BUG= none
R=jvoung@chromium.org, kschimpf@google.com

Committed: https://gerrit.chromium.org/gerrit/gitweb?p=native_client/pnacl-subzero.git;a=commit;h=6e861d5fe6b3222e8b179962275a57da64e3b825

[Jim Stichnoth, 2015-02-03 21:57:10]

stichnot@chromium.org changed reviewers:
+ jvoung@chromium.org, kschimpf@google.com

[Karl, 2015-02-03 22:00:43]

lgtm

[jvoung (off chromium), 2015-02-03 22:21:37]

lgtm -- oops!

[Jim Stichnoth, 2015-02-03 22:35:54]

Committed patchset #2 (id:20001) manually as
6e861d5fe6b3222e8b179962275a57da64e3b825 (presubmit successful).