Subzero: Change the szbuild.py --force default.

Makefile.standalone

 # The following variables will likely need to be modified, depending on where
 # and how you built LLVM & Clang. They can be overridden in a command-line
 # invocation of make, like:
 #
 #   make LLVM_SRC_PATH=<path> LIBCXX_INSTALL_PATH=<path> CLANG_PATH=<path> \
 #        PNACL_BIN_PATH=<path> ...
 #
 
 # LLVM_SRC_PATH is the path to the root of the checked out source code. This
 # directory should contain the configure script, the include/ and lib/
@@ skipping 455 matching lines @@
   SPEC := -O2 --filetype=obj
 endif
 ifeq ($(TARGET),arm32)
   TARGETFLAG=arm32
   SETUP=SetupGccArmOpt
   SPEC := -O2 --filetype=asm
 endif
 SPECFLAGS :=
 SPECBUILDONLY := false
 %.spec2k: % $(OBJDIR)/pnacl-sz make_symlink runtime
-        ./pydir/szbuild_spec2k.py -v --force \
+        ./pydir/szbuild_spec2k.py -v \
           $(SPECFLAGS) --target=$(TARGETFLAG) $(SPEC) $<
         $(SPECBUILDONLY) || ( cd ../../../tests/spec2k; \
          ./run_all.sh RunTimedBenchmarks $(SETUP) train $< )
 
 check-spec: $(ALLSPEC:=.spec2k)
 
 check: check-lit check-unit check-xtest
 
 check-presubmit presubmit:
 # Make sure clang-format gets run.
@@ skipping 54 matching lines @@
         @echo See Subzero size breakdown in bloat/pnacl-sz.bloat.html
 
 docs:
         make -C docs -f Makefile.standalone
 
 clean:
         rm -rf pnacl-sz *.o $(OBJDIR) $(SB_OBJDIR) build/pnacl-sz.bloat.json
 
 clean-all: clean
         rm -rf build/  crosstest/Output/