[NFC] fix trivial typos in comments and error message

"is is" -> "is", "are are" -> "are"

llvm-svn: 329546
diff --git a/llvm/lib/DebugInfo/PDB/GenericError.cpp b/llvm/lib/DebugInfo/PDB/GenericError.cpp
index 4fcecb9..2a677b9 100644
--- a/llvm/lib/DebugInfo/PDB/GenericError.cpp
+++ b/llvm/lib/DebugInfo/PDB/GenericError.cpp
@@ -30,7 +30,7 @@
       return "Type server PDB was not found.";
     case generic_error_code::dia_sdk_not_present:
       return "LLVM was not compiled with support for DIA.  This usually means "
-             "that you are are not using MSVC, or your Visual Studio "
+             "that you are not using MSVC, or your Visual Studio "
              "installation "
              "is corrupt.";
     case generic_error_code::invalid_path: