Update llvm-c headers for Version 11.0.1

src/llvm-c/Transforms/InstCombine.h

@@ -15,11 +15,10 @@
 #ifndef LLVM_C_TRANSFORMS_INSTCOMBINE_H
 #define LLVM_C_TRANSFORMS_INSTCOMBINE_H
 
+#include "../ExternC.h"
 #include "../Types.h"
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+LLVM_C_EXTERN_C_BEGIN
 
 /**
  * @defgroup LLVMCTransformsInstCombine Instruction Combining transformations
@@ -35,9 +34,7 @@ void LLVMAddInstructionCombiningPass(LLVMPassManagerRef PM);
  * @}
  */
 
-#ifdef __cplusplus
-}
-#endif /* defined(__cplusplus) */
+LLVM_C_EXTERN_C_END
 
 #endif