Refactor llvm2ice so that Ice can be built while reading bitcode.

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> LLVM_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/
 # directories of LLVM, Clang in tools/clang/, etc.
@@ skipping 18 matching lines @@
 # It's recommended that CXX matches the compiler you used to build LLVM itself.
 OPTLEVEL := -O0
 CXX := g++
 CXXFLAGS := -Wall -Wextra -Werror -fno-rtti -fno-exceptions \
         $(OPTLEVEL) -g $(LLVM_CXXFLAGS) -m32
 LDFLAGS := -m32
 
 SRCS= \
         IceCfg.cpp \
         IceCfgNode.cpp \
+        IceConverter.cpp \
         IceGlobalContext.cpp \
         IceInst.cpp \
         IceInstX8632.cpp \
         IceIntrinsics.cpp \
         IceLiveness.cpp \
         IceOperand.cpp \
         IceRegAlloc.cpp \
         IceTargetLowering.cpp \
         IceTargetLoweringX8632.cpp \
         IceTypes.cpp \
@@ skipping 23 matching lines @@
         $(LLVM_SRC_PATH)/utils/lit/lit.py -sv tests_lit
         (cd crosstest; LLVM_BIN_PATH=$(LLVM_BIN_PATH) ./runtests.sh)
 
 # TODO: Fix the use of wildcards.
 format:
         $(LLVM_BIN_PATH)/clang-format -style=LLVM -i \
         src/Ice*.h src/Ice*.cpp src/llvm2ice.cpp
 
 clean:
         rm -rf llvm2ice *.o build/