[llvm-c] Implement LLVMPrintValueToString

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194135 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm-c/Core.h

@@ -1211,6 +1211,14 @@ void LLVMSetValueName(LLVMValueRef Val, const char *Name);
  */
 void LLVMDumpValue(LLVMValueRef Val);
 
+/**
+ * Return a string representation of the value. Use
+ * LLVMDisposeMessage to free the string.
+ *
+ * @see llvm::Value::print()
+ */
+char *LLVMPrintValueToString(LLVMValueRef Val);
+
 /**
  * Replace all uses of a value with another one.
  *