Add support for LLVM_REPOSITORY_STRING.

[srhines]

Summary

Without this, vendor Clang builds can occasionally pick up an arbitrary
mirror location for the repository (at least on Android builds). This
allows vendor builds to be more reproducible.

[srhines]

I'm going to solve this a different way.

CMakeLists.txt

 
 set(CLANG_REPOSITORY_STRING "" CACHE STRING
   "Vendor-specific text for showing the repository the source is taken from.")
 
 if(CLANG_REPOSITORY_STRING)
   add_definitions(-DCLANG_REPOSITORY_STRING="${CLANG_REPOSITORY_STRING}")
 endif()
 
+set(LLVM_REPOSITORY_STRING "" CACHE STRING
+  "Vendor-specific text for showing the repository the LLVM source is taken from.")
+
+if(LLVM_REPOSITORY_STRING)
+  add_definitions(-DLLVM_REPOSITORY_STRING="${LLVM_REPOSITORY_STRING}")
+endif()
+
 set(CLANG_VENDOR_UTI "org.llvm.clang" CACHE STRING
   "Vendor-specific uti.")
 
 # The libdir suffix must exactly match whatever LLVM's configuration used.
 set(CLANG_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}")
 
 set(CLANG_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(CLANG_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})

lib/Basic/Version.cpp

#endif
   if (Start != StringRef::npos)
     URL = URL.substr(Start + 4);
 
   return URL;
 #endif
 }
 
 std::string getLLVMRepositoryPath() {
+#if defined(LLVM_REPOSITORY_STRING)
+  return LLVM_REPOSITORY_STRING;
+#else
 #ifdef LLVM_REPOSITORY
   StringRef URL(LLVM_REPOSITORY);
 #else
   StringRef URL("");
 #endif
 
   // Trim path prefix off, assuming path came from standard llvm path.
   // Leave "llvm/" prefix to distinguish the following llvm revision from the
   // clang revision.
   size_t Start = URL.find("llvm/");
   if (Start != StringRef::npos)
     URL = URL.substr(Start);
 
   return URL;
+#endif
 }
 
 std::string getClangRevision() {
 #ifdef SVN_REVISION
   return SVN_REVISION;
 #else
   return "";
 #endif