clang: Don't show a trailing space with --version when not built from the repo

[sylvestre.ledru]

Summary

Reported here:
https://bugs.llvm.org/show_bug.cgi?id=38998#c15

clang/lib/Basic/Version.cpp

 }
 
 std::string getClangToolFullVersion(StringRef ToolName) {
   std::string buf;
   llvm::raw_string_ostream OS(buf);
 #ifdef CLANG_VENDOR
   OS << CLANG_VENDOR;
 #endif
-  OS << ToolName << " version " CLANG_VERSION_STRING " "
-     << getClangFullRepositoryVersion();
+  OS << ToolName << " version " CLANG_VERSION_STRING;
+
+  std::string repo = getClangFullRepositoryVersion();
+  if (!repo.empty()) {
+    OS << " " << repo;
+  }
 
   return OS.str();
 }
 
 std::string getClangFullCPPVersion() {
   // The version string we report in __VERSION__ is just a compacted version of
   // the one we report on the command line.
   std::string buf;
   llvm::raw_string_ostream OS(buf);
 #ifdef CLANG_VENDOR
   OS << CLANG_VENDOR;
 #endif
-  OS << "Clang " CLANG_VERSION_STRING " " << getClangFullRepositoryVersion();
+  OS << "Clang " CLANG_VERSION_STRING;
+
+  std::string repo = getClangFullRepositoryVersion();
+  if (!repo.empty()) {
+    OS << " " << repo;
+  }
+
   return OS.str();
 }
 
 } // end namespace clang