Update to use llvm/utils/GetSourceVersion to detect version number, instead of
assuming SVN. This should be fixed to not necessarily be an integer.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94081 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Makefile b/lib/Basic/Makefile
index 5bd4314..dc00450 100644
--- a/lib/Basic/Makefile
+++ b/lib/Basic/Makefile
@@ -20,7 +20,7 @@
 
 include $(LEVEL)/Makefile.common
 
-SVN_REVISION := $(shell cd $(PROJ_SRC_DIR)/../.. && svnversion)
+SVN_REVISION := $(shell $(LLVM_SRC_ROOT)/utils/GetSourceVersion $(PROJ_SRC_DIR)/../..)
 
 CPP.Defines += -I$(PROJ_SRC_DIR)/../../include -I$(PROJ_OBJ_DIR)/../../include \
          -DSVN_REVISION='"$(SVN_REVISION)"'