Update llvm-c headers for Version 11.0.1

src/llvm-c/Comdat.h

@@ -14,11 +14,10 @@
 #ifndef LLVM_C_COMDAT_H
 #define LLVM_C_COMDAT_H
 
+#include "ExternC.h"
 #include "Types.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+LLVM_C_EXTERN_C_BEGIN
 
 typedef enum {
   LLVMAnyComdatSelectionKind,        ///< The linker may choose any COMDAT.
@@ -68,8 +67,6 @@ LLVMComdatSelectionKind LLVMGetComdatSelectionKind(LLVMComdatRef C);
  */
 void LLVMSetComdatSelectionKind(LLVMComdatRef C, LLVMComdatSelectionKind Kind);
 
-#ifdef __cplusplus
-}
-#endif
+LLVM_C_EXTERN_C_END
 
 #endif