Resolved undefined Common::g_scm_branch error.

src/common/scm_rev.cpp.in

@@ -11,7 +11,7 @@
 namespace Common {
 
 const char g_scm_rev[]      = GIT_REV;
-const char g_scm_ref_spec[] = GIT_BRANCH;
+const char g_scm_branch[]   = GIT_BRANCH;
 const char g_scm_desc[]     = GIT_DESC;
 
 } // namespace